Ammolite
Encyclopedia
Ammolite is a rare and valuable opal
-like organic gemstone
found primarily along the eastern slopes of the Rocky Mountains
of North America
. It is made of the fossil
ized shells of ammonite
s, which in turn are composed primarily of aragonite
, the same mineral
that makes up nacre
ous pearl
s. It is one of several biogenic
gemstones; others include amber
and pearl
.1 In 1981, ammolite was given official gemstone status by the World Jewellery Confederation
, the same year commercial mining of ammolite began. It was designated the official gemstone of the Province
of Alberta
in 2004 and the official gemstone of the City of Lethbridge
in 2007.
Ammolite is also known as aapoak (Kainah for "small, crawling stone"), gem ammonite, calcentine, and korite. The latter is a trade name given to the gemstone by the Alberta-based mining company Korite International
, the first and largest commercial producer of ammolite.
of ammolite is variable, and aside from aragonite may include calcite
, silica, pyrite
, or other minerals. The shell itself may contain a number of trace elements, including: aluminium
; barium
; chromium
; copper
; iron
; magnesium
; manganese
; strontium
; titanium
; and vanadium
. Its crystallography
is orthorhombic. Its hardness
is 4.5–5.5, quite soft for a gemstone, and its specific gravity
is 2.60–2.85. The refractive index
of Canadian material (as measured via sodium
light, 589.3 nm) is as follows: α 1.522; β 1.672–1.673; γ 1.676–1.679; biaxial negative. Under ultraviolet
light, ammolite may fluoresce
a mustard yellow.
An iridescent
opal-like play of color is shown in fine specimens, mostly in shades of green and red; all the spectral color
s are possible, however. The iridescence is due to the microstructure of the aragonite: unlike most other gems, whose colors come from light absorption, the iridescent color of ammolite comes from interference with the light that rebounds from stacked layers of thin platelets that make up the aragonite. The thicker the layers, the more reds and greens are produced; the thinner the layers, the more blues and violets predominate. Reds and greens are the most commonly seen colors, owing to the greater fragility of the finer layers responsible for the blues. When freshly quarried, these colors are not especially dramatic; the material requires polishing and possibly other treatments in order to reveal the colors' full potential.
The ammolite itself is actually a very thin sheet, ca. 0.5–0.8 millimeters (0.02–0.03 inches) in thickness. Rarely is ammolite without its matrix, which is typically a grey to brown shale
, chalky clay
, or limestone
. So-called "frost shattering" is common; exposed to the elements and compressed by sediments, the thin ammolite tends to crack and flake; prolonged exposure to sunlight can also lead to bleaching. The cracking results in a tessellated appearance, sometimes described as a "dragon
skin" or "stained glass
window" pattern. Ammolite mined from deeper deposits may be entirely smooth or with a rippled surface. Occasionally a complete ammonite shell is recovered with its structure well-preserved: fine, convoluted lines delineate the shell chambers, and the overall shape is suggestive of a nautilus
. While these shells may be as large as 90 centimeters (35.5 inches) in diameter, the iridescent ammonites (as opposed to the pyritized variety) are typically much smaller. Most fossilized shells have had their aragonite pseudomorph
ously replaced by calcite or pyrite, making the presence of ammolite particularly uncommon.
Ammolite comes from the fossil shells of the Upper Cretaceous
disk-shaped ammonites Placenticeras meeki and Placenticeras intercalare, and (to a lesser degree) the cylindrical baculite
, Baculites compressus. Ammonites were cephalopod
s, or squid
-like creatures, that thrived in tropical seas until becoming extinct
along with the dinosaur
s at the end of the Mesozoic
era.
The ammonites that form ammolite inhabited a prehistoric, inland subtropical sea that bordered the Rocky Mountains—this area is known today as the Cretaceous or Western Interior Seaway
. As the seas receded, the ammonites were buried by layers of bentonite
sediment
. This sediment preserved the aragonite of their shelled remains, preventing it from converting to calcite
.
Significant deposits of gem-quality ammolite are only found in the Bearpaw formation that extends from Alberta to Saskatchewan
in Canada and south to Montana
in the USA. The best grade of gem quality ammolite is along high energy river systems on the eastern slopes of the Rockies in southern Alberta. Most commercial mining operations have been conducted along the banks of the St. Mary River, in an area south of and between the town of Magrath and the city of Lethbridge. Roughly half of all ammolite deposits are contained within the Kainah (Kainaiwa) reserve
, and its inhabitants play a major role in ammolite mining. Since its founding in 1979, Korite International has operated primarily within the reservation. The company maintains an agreement with the Kainah (Blood) tribe
, with Korite International paying the tribe royalties based on how much land the company has mined.
Commercial extraction is mechanized but fairly basic: shallow open pit
s are dug with a backhoe
and the excavated material is screened for its potential gem contents. The pits are further examined by hand, and commercial production is supplemented by individuals who sell their surface-picked findings to Korite International and several other producers. Approximately 50% of the ammolite mined is suitable for jewelry.
The ammolite deposits are stratified into several layers: the shallowest of these layers, named the "K Zone", lies some 15 meters below the surface and extends 30 meters down. The ammolite within this layer is covered by siderite
concretion
s and is usually cracked—this is the crush material. It is the most common and (generally speaking) the least valuable of ammolite. Beginning twenty meters below the crush material is the "Blue Zone"; ammolite from this zone, which extends 65 meters, is usually compressed with a thin layer of pyrite
rather than siderite
concretions. This is the sheet material; due to its depth it is rarely mined. It is also much less fractured, and therefore the more valuable type of ammolite.
, Korite International had only mined 30 acre
s (120,000 m²) of the Kainah deposit. As part of their agreement with the tribe, the company must refill areas once exhausted to mitigate environmental degradation
. Korite International's operations net the Kainah tribe approximately CAD
150,000–200,000 per year. The company employs over 60 people (many of them Kainah), and accounts for approximately 90 percent of world gem ammolite production. Prospectors
who wish to mine ammolite deposits on Crown land
must apply to the Alberta Department of Energy for a lease. These leases are not regularly offered; as of 2004, there was a CAD 625 application fee, with an annual rental fee of CAD $3.50 per hectare
http://www.energy.gov.ab.ca/2803.asp.
The number of primary colors : A large array of color is displayed in ammolite, including all the spectral colors found in nature. Red and green are far more common than blue or purple due to the latter's fragility (see properties). There are also certain hues, like crimson or violet or gold, which are derived from a combination of the primary color
s, that are the rarest and in highest demand. The most valuable grades have roughly equal portions of three or more primary colors or 1–2 bright and even colors, with the lowest grades having one comparatively dull color predominant.
The way the colors play (chromatic shift and rotational range) : Chromatic shift is how the colors vary with the angle of viewing and the angle of light striking
the gemstone; in higher grades this variation is almost prismatic
in its scope, while lower grades show very little variation. Rotational range is how far the specimen can be turned while maintaining its play of color; the best rotate 360 degrees uncompromised, while lesser stones may exhibit highly directional colors that are only visible within a narrow rotational range, down to 90° or less. Intermediate grades have ranges of 240–180°.
Brightness of colors (iridescence) : The brightness of colors and their iridescence
is essentially dependent on how well-preserved the nacreous shell is, and how fine and orderly the layers of aragonite are. The quality of the polish is also a factor. The "dragon skin" cracking usually hinders its value; the most prized ammolite is the sheet type (see formation) and has broad, uninterrupted swathes of color similar to the "broad flash" category of opal. The matrix is not visible in finer grades, and there should be no foreign minerals breaking up or diminishing the iridescence.
The thickness of the ammolite layer is also an important factor: after polishing, the ammolite is only 0.1–0.3 millimeters thick. The rarest and most valuable are thick enough to stand alone, with only a thin portion of its original matrix (not exceeding 1.5 mm); but the vast majority require some sort of supportive backing. Other treatments are also commonly undertaken; all other factors being equal, the less treatment an ammolite gem has received, the more valuable it is. Calibrated stones—that is, stones fashioned into standard dimensions that will fit most jewelry settings—may also command a higher price.
Ammolite is sold for USD $30 to 65 per carat (150 to 325 $/g).
—and therefore not subject to dehydration and subsequent crazing as seen in opal—ammolite is often damaged due to environmental exposure. The thin, delicate sheets in which ammolite occurs are also problematic; for these reasons, most material is impregnated with a clear epoxy
or other synthetic resin to stabilize the flake-prone ammolite prior to cutting. Although the tessellated cracking cannot be repaired, the epoxy prevents further flaking and helps protect the relatively soft surface from scratching. The impregnation process was developed over a number of years by Korite International in partnership with the Alberta Research Council. Impregnated and epoxy-coated ammolite first entered the market in 1989 and the treatment significantly increased the availability of the gem.
Because the ammolite layer is usually mere fractions of a millimeter in thickness, most ammolite gems are in fact composite stones: these usually take the form of two-part doublets, with the ammolite layer adhered to a dark backing material. This is usually the matrix or mother rock from which the ammolite was quarried; black onyx
or glass
could also be used as backing. In composites where the ammolite layer is exceptionally thin, a third component is used: this constitutes a triplet, with a durable and transparent convex topping piece. This cap may be either synthetic spinel
, synthetic corundum
, synthetic quartz
, or in lower-end productions, glass. The convex cap acts as a lens
and has the effect of enhancing the ammolite's iridescent display.
The detection of these treated and composite stones is relatively simple via inspection with a loupe
; however, certain jewelry setting styles—such as those with closed backs—can complicate things. A triplet can be identified by inspecting the stone in profile; the top of the stone can then be seen to be domed and transparent, with no play of color. If the dome is made of glass, bubbles, swirl marks, and scratches may be present; the harder synthetic materials are optically flawless.
Although the vast majority of commercial-grade ammolite has been treated in some way, a small fraction of production requires no treatment other than cutting and polishing. Ideally, any treatments should be disclosed at the time of sale.
Ammolite is neither easily nor often imitated; however, a few materials have a passing resemblance that may deceive the unfamiliar. These include: labradorite
(also known as spectrolite
), an iridescent feldspar
also of Canadian origin; and broad-flash black opal. Neither are convincing substitutes, and the latter is actually of greater value than ammolite. Indeed, ammolite is often used as an imitation of black opal. An even less convincing possibility is Slocum stone
, a common glass-based imitation of opal. Blues and purples are much more pervasive in labradorite, and in both it and opal the play of color is seen to roll across the stone unlike the comparatively restricted play of color in ammolite. In Slocum stone, the play of color takes the form of tinsel-like patches. The visible structure is also considerably different; in the imitations, the body of the stone is transparent to translucent from certain angles, whereas ammolite is entirely opaque.
Gemologically
speaking, ammolite can be grouped with the shell-based marble
s. This group includes lumachella or "fire marble", a similarly iridescent marble composed of fossilized clam
and snail
shells. Found in Italy
and Austria
, lumachella is rarely if ever used in jewelry; rather, it is used as a decorative facing stone or in mosaic
s. The iridescence of lumachella is fragmentary and not nearly as brilliant as that of ammolite. Despite these differences, lumachella may be considered synonymous with ammolite in some circles.
The predominantly blue-green iridescent shell of abalone
(or paua; genus
Haliotis) is one last possible imitation. Abalone shell is inexpensive and plentiful owing to the commercial mariculture
of these gastropods for their meat. The shell's structure is distinctive: sinuous bands of blue, green, and rose iridescence are delineated by dark brown lines of conchiolin
, a protein
aceous material that holds the shell together. The luster
of abalone shell is silky rather than the near vitreous luster of polished ammolite, and the colors of the two materials do not closely approximate. However, some abalone shell has been dye
d and given a transparent cap of synthetic quartz, forming a doublet in the same fashion as ammolite. These doublets are perhaps the most deceptive, and have also been used to imitate opal. Under magnification most abalone doublets will show dye concentrated along certain areas and air bubbles trapped at the shell-quartz interface.
Compared to most other gems, ammolite has a rather scant history of use; it did not begin to garner interest in Western society until the 1970s after entering the market (to a limited degree) in 1969. The Blackfeet
tribe know ammolite as iniskim, meaning "buffalo
stone", and have long believed it to possess amulet
ic powers; specifically, the gem is believed to aid in the buffalo hunt, and to draw the buffalo within tracking distance. The Blackfeet also believe ammolite to possess healing powers and incorporate the gem into their medicine bundle
s for use in ceremonies.
In the late 1990s, practitioners of Feng Shui
began to promote ammolite as an "influential" stone with what they believe is the power to enhance well-being and detoxify the body by improving its flow of energy or "chi
". Named the "Seven Color Prosperity Stone", each color is believed by Feng Shui practitioners to influence the wearer in different and positive ways; a combination of ruby
red, emerald
green, and amber
yellow is most sought after for this purpose, the colors being said to enhance growth, wisdom, and wealth, respectively.
Ammolite is usually fashioned into freeform cabochon
s and mounted in gold
, with diamond
s as accents. Due to its delicacy, ammolite is best reserved for use in pendant
s, earring
s, and brooch
es; if used as a ring
stone, ammolite should be given a hard protective cap, namely one of synthetic spinel as used in triplets. Whole polished ammonites of appropriately small size may also be mounted in jewelry. Nothing harsher than mild soap and warm water should be used to clean ammolite jewelry; ultrasonic
cleaning should be avoided.
Japan
is the largest market for ammolite; this may be due to its use as an imitation of increasingly scarce black opal, or its aforementioned use in Feng Shui. Secondary markets include Canada, where it is used both by artisan
s who sell their creations to tourists of Banff National Park
and in fine jewelry production; and the Southwest United States, where it is used by Zuni and other Native American
craftspeople.
Opal
Opal is an amorphous form of silica related to quartz, a mineraloid form, not a mineral. 3% to 21% of the total weight is water, but the content is usually between 6% to 10%. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most...
-like organic gemstone
Gemstone
A gemstone or gem is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments...
found primarily along the eastern slopes of the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It is made of the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
ized shells of ammonite
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
s, which in turn are composed primarily of aragonite
Aragonite
Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
, the same mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
that makes up nacre
Nacre
Nacre , also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent....
ous pearl
Pearl
A pearl is a hard object produced within the soft tissue of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other...
s. It is one of several biogenic
Biogenic substance
A biogenic substance is a substance produced by life processes. It may be either constituents, or secretions, of plants or animals. A more specific name for these substances is biomolecules.-Examples:...
gemstones; others include amber
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
and pearl
Pearl
A pearl is a hard object produced within the soft tissue of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other...
.1 In 1981, ammolite was given official gemstone status by the World Jewellery Confederation
CIBJO
The CIBJO , also known as the World Jewellery Confederation, is an international confederation of jewellery, gemstone, horology, and silverware trade organisations...
, the same year commercial mining of ammolite began. It was designated the official gemstone of the Province
Provinces and territories of Canada
The provinces and territories of Canada combine to make up the world's second-largest country by area. There are ten provinces and three territories...
of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
in 2004 and the official gemstone of the City of Lethbridge
Lethbridge
Lethbridge is a city in the province of Alberta, Canada, and the largest city in southern Alberta. It is Alberta's fourth-largest city by population after Calgary, Edmonton and Red Deer, and the third-largest by area after Calgary and Edmonton. The nearby Canadian Rockies contribute to the city's...
in 2007.
Ammolite is also known as aapoak (Kainah for "small, crawling stone"), gem ammonite, calcentine, and korite. The latter is a trade name given to the gemstone by the Alberta-based mining company Korite International
Korite International
Korite International is the largest commercial producer of ammolite. It is based in Alberta, Canada. The firm's sister company, Canada Fossils Ltd., provides it with ammonites and other fossils...
, the first and largest commercial producer of ammolite.
Properties
The chemical compositionAnalytical chemistry
Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...
of ammolite is variable, and aside from aragonite may include calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, silica, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, or other minerals. The shell itself may contain a number of trace elements, including: aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
; barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
; chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
; copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
; iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
; magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
; manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
; strontium
Strontium
Strontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
; titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
; and vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
. Its crystallography
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
is orthorhombic. Its hardness
Mohs scale of mineral hardness
The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...
is 4.5–5.5, quite soft for a gemstone, and its specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
is 2.60–2.85. The refractive index
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
of Canadian material (as measured via sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
light, 589.3 nm) is as follows: α 1.522; β 1.672–1.673; γ 1.676–1.679; biaxial negative. Under ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light, ammolite may fluoresce
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
a mustard yellow.
An iridescent
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...
opal-like play of color is shown in fine specimens, mostly in shades of green and red; all the spectral color
Spectral color
A spectral color is a color that is evoked by a single wavelength of light in the visible spectrum, or by a relatively narrow band of wavelengths...
s are possible, however. The iridescence is due to the microstructure of the aragonite: unlike most other gems, whose colors come from light absorption, the iridescent color of ammolite comes from interference with the light that rebounds from stacked layers of thin platelets that make up the aragonite. The thicker the layers, the more reds and greens are produced; the thinner the layers, the more blues and violets predominate. Reds and greens are the most commonly seen colors, owing to the greater fragility of the finer layers responsible for the blues. When freshly quarried, these colors are not especially dramatic; the material requires polishing and possibly other treatments in order to reveal the colors' full potential.
The ammolite itself is actually a very thin sheet, ca. 0.5–0.8 millimeters (0.02–0.03 inches) in thickness. Rarely is ammolite without its matrix, which is typically a grey to brown shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
, chalky clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
, or limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
. So-called "frost shattering" is common; exposed to the elements and compressed by sediments, the thin ammolite tends to crack and flake; prolonged exposure to sunlight can also lead to bleaching. The cracking results in a tessellated appearance, sometimes described as a "dragon
Dragon
A dragon is a legendary creature, typically with serpentine or reptilian traits, that feature in the myths of many cultures. There are two distinct cultural traditions of dragons: the European dragon, derived from European folk traditions and ultimately related to Greek and Middle Eastern...
skin" or "stained glass
Stained glass
The term stained glass can refer to coloured glass as a material or to works produced from it. Throughout its thousand-year history, the term has been applied almost exclusively to the windows of churches and other significant buildings...
window" pattern. Ammolite mined from deeper deposits may be entirely smooth or with a rippled surface. Occasionally a complete ammonite shell is recovered with its structure well-preserved: fine, convoluted lines delineate the shell chambers, and the overall shape is suggestive of a nautilus
Nautilus
Nautilus is the common name of marine creatures of cephalopod family Nautilidae, the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in two genera, the type of which is the genus Nautilus...
. While these shells may be as large as 90 centimeters (35.5 inches) in diameter, the iridescent ammonites (as opposed to the pyritized variety) are typically much smaller. Most fossilized shells have had their aragonite pseudomorph
Pseudomorph
In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form , resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by another...
ously replaced by calcite or pyrite, making the presence of ammolite particularly uncommon.
Formation, occurrence, and extraction
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
disk-shaped ammonites Placenticeras meeki and Placenticeras intercalare, and (to a lesser degree) the cylindrical baculite
Baculite
Baculites is an extinct cephalopod genus with a nearly straight shell that is included in the heteromorph ammonites...
, Baculites compressus. Ammonites were cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s, or squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
-like creatures, that thrived in tropical seas until becoming extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
along with the dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s at the end of the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
era.
The ammonites that form ammolite inhabited a prehistoric, inland subtropical sea that bordered the Rocky Mountains—this area is known today as the Cretaceous or Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
. As the seas receded, the ammonites were buried by layers of bentonite
Bentonite
Bentonite is an absorbent aluminium phyllosilicate, essentially impure clay consisting mostly of montmorillonite. There are different types of bentonite, each named after the respective dominant element, such as potassium , sodium , calcium , and aluminum . Experts debate a number of nomenclatorial...
sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
. This sediment preserved the aragonite of their shelled remains, preventing it from converting to calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
.
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
in Canada and south to Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
in the USA. The best grade of gem quality ammolite is along high energy river systems on the eastern slopes of the Rockies in southern Alberta. Most commercial mining operations have been conducted along the banks of the St. Mary River, in an area south of and between the town of Magrath and the city of Lethbridge. Roughly half of all ammolite deposits are contained within the Kainah (Kainaiwa) reserve
Indian reserve
In Canada, an Indian reserve is specified by the Indian Act as a "tract of land, the legal title to which is vested in Her Majesty, that has been set apart by Her Majesty for the use and benefit of a band." The Act also specifies that land reserved for the use and benefit of a band which is not...
, and its inhabitants play a major role in ammolite mining. Since its founding in 1979, Korite International has operated primarily within the reservation. The company maintains an agreement with the Kainah (Blood) tribe
Kainai Nation
The Kainai Nation is a First Nation in southern Alberta, Canada with a population of 7,437 members in 2005, and had a population of 9,035 members as of 9 February 2008...
, with Korite International paying the tribe royalties based on how much land the company has mined.
Open-pit mining
Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow....
s are dug with a backhoe
Backhoe
A backhoe, also called a rear actor or back actor, is a piece of excavating equipment or digger consisting of a digging bucket on the end of a two-part articulated arm. They are typically mounted on the back of a tractor or front loader...
and the excavated material is screened for its potential gem contents. The pits are further examined by hand, and commercial production is supplemented by individuals who sell their surface-picked findings to Korite International and several other producers. Approximately 50% of the ammolite mined is suitable for jewelry.
The ammolite deposits are stratified into several layers: the shallowest of these layers, named the "K Zone", lies some 15 meters below the surface and extends 30 meters down. The ammolite within this layer is covered by siderite
Siderite
Siderite is a mineral composed of iron carbonate FeCO3. It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus...
concretion
Concretion
A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity . Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and crescere meaning 'to grow'...
s and is usually cracked—this is the crush material. It is the most common and (generally speaking) the least valuable of ammolite. Beginning twenty meters below the crush material is the "Blue Zone"; ammolite from this zone, which extends 65 meters, is usually compressed with a thin layer of pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
rather than siderite
Siderite
Siderite is a mineral composed of iron carbonate FeCO3. It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus...
concretions. This is the sheet material; due to its depth it is rarely mined. It is also much less fractured, and therefore the more valuable type of ammolite.
, Korite International had only mined 30 acre
Acre
The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...
s (120,000 m²) of the Kainah deposit. As part of their agreement with the tribe, the company must refill areas once exhausted to mitigate environmental degradation
Environmental degradation
Environmental degradation is the deterioration of the environment through depletion of resources such as air, water and soil; the destruction of ecosystems and the extinction of wildlife...
. Korite International's operations net the Kainah tribe approximately CAD
Canadian dollar
The Canadian dollar is the currency of Canada. As of 2007, the Canadian dollar is the 7th most traded currency in the world. It is abbreviated with the dollar sign $, or C$ to distinguish it from other dollar-denominated currencies...
150,000–200,000 per year. The company employs over 60 people (many of them Kainah), and accounts for approximately 90 percent of world gem ammolite production. Prospectors
Prospecting
Prospecting is the physical search for minerals, fossils, precious metals or mineral specimens, and is also known as fossicking.Prospecting is a small-scale form of mineral exploration which is an organised, large scale effort undertaken by mineral resource companies to find commercially viable ore...
who wish to mine ammolite deposits on Crown land
Crown land
In Commonwealth realms, Crown land is an area belonging to the monarch , the equivalent of an entailed estate that passed with the monarchy and could not be alienated from it....
must apply to the Alberta Department of Energy for a lease. These leases are not regularly offered; as of 2004, there was a CAD 625 application fee, with an annual rental fee of CAD $3.50 per hectare
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...
http://www.energy.gov.ab.ca/2803.asp.
Gemstone quality
The quality of gem ammolite is communicated via a letter grade system, from best to least best: AA; A+; A; and A-. However, this system is not yet standardized and some vendors may use their own systems. The grade and therefore the value of an ammolite gemstone is determined by the following criteria:The number of primary colors : A large array of color is displayed in ammolite, including all the spectral colors found in nature. Red and green are far more common than blue or purple due to the latter's fragility (see properties). There are also certain hues, like crimson or violet or gold, which are derived from a combination of the primary color
Primary color
Primary colors are sets of colors that can be combined to make a useful range of colors. For human applications, three primary colors are usually used, since human color vision is trichromatic....
s, that are the rarest and in highest demand. The most valuable grades have roughly equal portions of three or more primary colors or 1–2 bright and even colors, with the lowest grades having one comparatively dull color predominant.
The way the colors play (chromatic shift and rotational range) : Chromatic shift is how the colors vary with the angle of viewing and the angle of light striking
Angle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...
the gemstone; in higher grades this variation is almost prismatic
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
in its scope, while lower grades show very little variation. Rotational range is how far the specimen can be turned while maintaining its play of color; the best rotate 360 degrees uncompromised, while lesser stones may exhibit highly directional colors that are only visible within a narrow rotational range, down to 90° or less. Intermediate grades have ranges of 240–180°.
Brightness of colors (iridescence) : The brightness of colors and their iridescence
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...
is essentially dependent on how well-preserved the nacreous shell is, and how fine and orderly the layers of aragonite are. The quality of the polish is also a factor. The "dragon skin" cracking usually hinders its value; the most prized ammolite is the sheet type (see formation) and has broad, uninterrupted swathes of color similar to the "broad flash" category of opal. The matrix is not visible in finer grades, and there should be no foreign minerals breaking up or diminishing the iridescence.
The thickness of the ammolite layer is also an important factor: after polishing, the ammolite is only 0.1–0.3 millimeters thick. The rarest and most valuable are thick enough to stand alone, with only a thin portion of its original matrix (not exceeding 1.5 mm); but the vast majority require some sort of supportive backing. Other treatments are also commonly undertaken; all other factors being equal, the less treatment an ammolite gem has received, the more valuable it is. Calibrated stones—that is, stones fashioned into standard dimensions that will fit most jewelry settings—may also command a higher price.
Ammolite is sold for USD $30 to 65 per carat (150 to 325 $/g).
Treatments
Although fully mineralized and containing no waterWater
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
—and therefore not subject to dehydration and subsequent crazing as seen in opal—ammolite is often damaged due to environmental exposure. The thin, delicate sheets in which ammolite occurs are also problematic; for these reasons, most material is impregnated with a clear epoxy
Epoxy
Epoxy, also known as polyepoxide, is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives....
or other synthetic resin to stabilize the flake-prone ammolite prior to cutting. Although the tessellated cracking cannot be repaired, the epoxy prevents further flaking and helps protect the relatively soft surface from scratching. The impregnation process was developed over a number of years by Korite International in partnership with the Alberta Research Council. Impregnated and epoxy-coated ammolite first entered the market in 1989 and the treatment significantly increased the availability of the gem.
Because the ammolite layer is usually mere fractions of a millimeter in thickness, most ammolite gems are in fact composite stones: these usually take the form of two-part doublets, with the ammolite layer adhered to a dark backing material. This is usually the matrix or mother rock from which the ammolite was quarried; black onyx
Onyx
Onyx is a banded variety of chalcedony. The colors of its bands range from white to almost every color . Commonly, specimens of onyx contain bands of black and/or white.-Etymology:...
or glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
could also be used as backing. In composites where the ammolite layer is exceptionally thin, a third component is used: this constitutes a triplet, with a durable and transparent convex topping piece. This cap may be either synthetic spinel
Spinel
Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4. Balas ruby is an old name for a rose-tinted variety.-Spinel group:...
, synthetic corundum
Corundum
Corundum is a crystalline form of aluminium oxide with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally clear transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red...
, synthetic quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, or in lower-end productions, glass. The convex cap acts as a lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
and has the effect of enhancing the ammolite's iridescent display.
The detection of these treated and composite stones is relatively simple via inspection with a loupe
Loupe
A loupe is a simple, small magnification device used to see small details more closely. Unlike a magnifying glass, a loupe does not have an attached handle, and its focusing lens are contained in an opaque cylinder or cone. Loupes are also called hand lenses .- Optics :Three basic types of loupes...
; however, certain jewelry setting styles—such as those with closed backs—can complicate things. A triplet can be identified by inspecting the stone in profile; the top of the stone can then be seen to be domed and transparent, with no play of color. If the dome is made of glass, bubbles, swirl marks, and scratches may be present; the harder synthetic materials are optically flawless.
Although the vast majority of commercial-grade ammolite has been treated in some way, a small fraction of production requires no treatment other than cutting and polishing. Ideally, any treatments should be disclosed at the time of sale.
Imitations
Labradorite
Labradorite , a feldspar mineral, is an intermediate to calcic member of the plagioclase series. It is usually defined as having "%An" between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573....
(also known as spectrolite
Spectrolite
Spectrolite is a rare variety of labradorite feldspar which exhibits intense labradorescence, schiller or iridescence. The variety is a trade name for material mined in Finland. Labradorite with the spectrolite play of colors has also reported from Madagascar. It is noted for the play of colors...
), an iridescent feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
also of Canadian origin; and broad-flash black opal. Neither are convincing substitutes, and the latter is actually of greater value than ammolite. Indeed, ammolite is often used as an imitation of black opal. An even less convincing possibility is Slocum stone
Slocum stone
Slocum stone is an early opal simulant which was briefly popular prior to the introduction of synthetics and less expensive simulants. It was named after its inventor, John S. Slocum of Rochester, Michigan....
, a common glass-based imitation of opal. Blues and purples are much more pervasive in labradorite, and in both it and opal the play of color is seen to roll across the stone unlike the comparatively restricted play of color in ammolite. In Slocum stone, the play of color takes the form of tinsel-like patches. The visible structure is also considerably different; in the imitations, the body of the stone is transparent to translucent from certain angles, whereas ammolite is entirely opaque.
Gemologically
Gemology
Gemology or gemmology is the science dealing with natural and artificial gems and gemstones. It is considered a geoscience and a branch of mineralogy...
speaking, ammolite can be grouped with the shell-based marble
Marble
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite.Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.Marble is commonly used for...
s. This group includes lumachella or "fire marble", a similarly iridescent marble composed of fossilized clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
and snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
shells. Found in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
and Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
, lumachella is rarely if ever used in jewelry; rather, it is used as a decorative facing stone or in mosaic
Mosaic
Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials. It may be a technique of decorative art, an aspect of interior decoration, or of cultural and spiritual significance as in a cathedral...
s. The iridescence of lumachella is fragmentary and not nearly as brilliant as that of ammolite. Despite these differences, lumachella may be considered synonymous with ammolite in some circles.
The predominantly blue-green iridescent shell of abalone
Abalone
Abalone , from aulón, are small to very large-sized edible sea snails, marine gastropod molluscs in the family Haliotidae and the genus Haliotis...
(or paua; genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Haliotis) is one last possible imitation. Abalone shell is inexpensive and plentiful owing to the commercial mariculture
Mariculture
Mariculture is a specialized branch of aquaculture involving the cultivation of marine organisms for food and other products in the open ocean, an enclosed section of the ocean, or in tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of marine fish,...
of these gastropods for their meat. The shell's structure is distinctive: sinuous bands of blue, green, and rose iridescence are delineated by dark brown lines of conchiolin
Conchiolin
Conchiolin and perlucin are complex proteins which are secreted by a mollusc's outer epithelium ....
, a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
aceous material that holds the shell together. The luster
Lustre (mineralogy)
Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....
of abalone shell is silky rather than the near vitreous luster of polished ammolite, and the colors of the two materials do not closely approximate. However, some abalone shell has been dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
d and given a transparent cap of synthetic quartz, forming a doublet in the same fashion as ammolite. These doublets are perhaps the most deceptive, and have also been used to imitate opal. Under magnification most abalone doublets will show dye concentrated along certain areas and air bubbles trapped at the shell-quartz interface.
Use in jewelry
Blackfeet
The Piegan Blackfeet are a tribe of Native Americans of the Algonquian language family based in Montana, having lived in this area since around 6,500 BC. Many members of the tribe live as part of the Blackfeet Nation in northwestern Montana, with population centered in Browning...
tribe know ammolite as iniskim, meaning "buffalo
American Bison
The American bison , also commonly known as the American buffalo, is a North American species of bison that once roamed the grasslands of North America in massive herds...
stone", and have long believed it to possess amulet
Amulet
An amulet, similar to a talisman , is any object intended to bring good luck or protection to its owner.Potential amulets include gems, especially engraved gems, statues, coins, drawings, pendants, rings, plants and animals; even words said in certain occasions—for example: vade retro satana—, to...
ic powers; specifically, the gem is believed to aid in the buffalo hunt, and to draw the buffalo within tracking distance. The Blackfeet also believe ammolite to possess healing powers and incorporate the gem into their medicine bundle
Medicine bundle
A medicine bundle is a wrapped package used by Native Americans for religious purposes. A package of this type can also be referred to as a medicine bag. Medicine bundles are usually employed as a ritual aid in Shamanistic religions...
s for use in ceremonies.
In the late 1990s, practitioners of Feng Shui
Feng shui
Feng shui ' is a Chinese system of geomancy believed to use the laws of both Heaven and Earth to help one improve life by receiving positive qi. The original designation for the discipline is Kan Yu ....
began to promote ammolite as an "influential" stone with what they believe is the power to enhance well-being and detoxify the body by improving its flow of energy or "chi
Qi
In traditional Chinese culture, qì is an active principle forming part of any living thing. Qi is frequently translated as life energy, lifeforce, or energy flow. Qi is the central underlying principle in traditional Chinese medicine and martial arts...
". Named the "Seven Color Prosperity Stone", each color is believed by Feng Shui practitioners to influence the wearer in different and positive ways; a combination of ruby
Ruby
A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum . The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires...
red, emerald
Emerald
Emerald is a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the 10 point Mohs scale of mineral hardness...
green, and amber
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
yellow is most sought after for this purpose, the colors being said to enhance growth, wisdom, and wealth, respectively.
Ammolite is usually fashioned into freeform cabochon
Cabochon
A cabochon , from the Middle French caboche , is a gemstone which has been shaped and polished as opposed to faceted. The resulting form is usually a convex top with a flat bottom. Cutting en cabochon is usually applied to opaque gems, while faceting is usually applied to transparent stones...
s and mounted in gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
, with diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
s as accents. Due to its delicacy, ammolite is best reserved for use in pendant
Pendant
A pendant is a loose-hanging piece of jewellery, generally attached by a small loop to a necklace, when the ensemble may be known as a "pendant necklace". A pendant earring is an earring with a piece hanging down. In modern French "pendant" is the gerund form of “hanging”...
s, earring
Earring
Common locations for piercings, other than the earlobe, include the rook, tragus, and across the helix . The simple term "ear piercing" usually refers to an earlobe piercing, whereas piercings in the upper part of the external ear are often referred to as "cartilage piercings"...
s, and brooch
Brooch
A brooch ; also known in ancient times as a fibula; is a decorative jewelry item designed to be attached to garments. It is usually made of metal, often silver or gold but sometimes bronze or some other material...
es; if used as a ring
Jewellery
Jewellery or jewelry is a form of personal adornment, such as brooches, rings, necklaces, earrings, and bracelets.With some exceptions, such as medical alert bracelets or military dog tags, jewellery normally differs from other items of personal adornment in that it has no other purpose than to...
stone, ammolite should be given a hard protective cap, namely one of synthetic spinel as used in triplets. Whole polished ammonites of appropriately small size may also be mounted in jewelry. Nothing harsher than mild soap and warm water should be used to clean ammolite jewelry; ultrasonic
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
cleaning should be avoided.
Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
is the largest market for ammolite; this may be due to its use as an imitation of increasingly scarce black opal, or its aforementioned use in Feng Shui. Secondary markets include Canada, where it is used both by artisan
Artisan
An artisan is a skilled manual worker who makes items that may be functional or strictly decorative, including furniture, clothing, jewellery, household items, and tools...
s who sell their creations to tourists of Banff National Park
Banff National Park
Banff National Park is Canada's oldest national park, established in 1885 in the Rocky Mountains. The park, located 110–180 kilometres west of Calgary in the province of Alberta, encompasses of mountainous terrain, with numerous glaciers and ice fields, dense coniferous forest, and alpine...
and in fine jewelry production; and the Southwest United States, where it is used by Zuni and other Native American
Native Americans in the United States
Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, parts of Alaska, and the island state of Hawaii. They are composed of numerous, distinct tribes, states, and ethnic groups, many of which survive as...
craftspeople.