Djurleite
Encyclopedia
Djurleite is a copper sulfide
mineral of secondary origin
with formula Cu31S16 that crystallizes with monoclinic
-prismatic symmetry. It is typically massive in form, but does at times develop thin tabular to prismatic crystals. It occurs with other supergene
minerals such as chalcocite
, covellite
and digenite
in the enriched zone of copper ore
bodies. It is a member of the chalcocite group, and very similar to chalcocite, Cu2S, in its composition and properties, but the two minerals can be distinguished from each other by x-ray powder diffraction. Intergrowths and transformations between djurleite, digenite and chalcocite are common. Many of the reported associations of digenite and djurleite, however, identified by powder diffraction, could be anilite and djurleite, as anilite transforms to digenite during grinding.
Djurleite was named for the Swedish chemist Seved Djurle (1918– ), from the University of Uppsala, Sweden, who first synthesized the mineral in 1958, prior to its discovery in nature. The natural material was first described in 1962 by E H Roseboom Jr, of the US Geological Survey, from occurrences at the type locality
, Barranca del Cobre
, Chihuahua, Mexico.
structure with a large unit cell containing 248 copper
and 128 sulfur
atoms. The formula is Cu31S16, molar mass
2483 g, and there are 8 formula units per unit cell (Z = 8).
The crystal class is 2/m, meaning the structure has an axis of twofold rotational symmetry perpendicular to a mirror plane
. The space group
is P21/c, and the unit cell parameters are a = 26.897 Å
, b = 15.745 Å, c = 13.565 Å and β = 90.13°. The structure is based on hexagonal closest packing of sulfur atoms with a monoclinic space group.
. Pseudohexagonal twins
are common, with crystal blocks rotated around the a crystal axis
, which is normal to the close-packed layers, by multiples of 60o. Djurleite is brittle, with a conchoidal (shell-like) fracture
. It is a soft mineral, with hardness 2½ to 3, a little less than that of calcite
. The specific gravity
, 5.63, is high, due to the copper content, djurleite is denser than the copper-iron sulfide bornite
, but not as dense as the iron-arsenic sulfide arsenopyrite
.
and a submetallic to metallic luster
. It is an opaque mineral, so refractive indices
are not defined. The reflectivity (the percentage of incident energy which is reflected from a surface) for light of wavelength
540 nm
varies between 29.6 and 30.2, and is slightly dependent on the direction of the incident light, that is to say, the mineral is weakly anisotropic.
of copper
deposits, associated with other secondary copper sulfides digenite
, chalcocite
, bornite
, chalcopyrite
and anilite with pyrite
.
, Toronto, Canada, M25369, and at the National Museum of Natural History
, Washington, DC, USA.
Copper sulfide
Copper sulfides describe a family of chemical compounds and minerals with the formula CuxSy. Both minerals and synthetic materials comprise these compounds. Some copper sulfides are economically important ores....
mineral of secondary origin
Supergene (geology)
In ore deposit geology, supergene processes or enrichment occur relatively near the surface. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary sulfide ore minerals and...
with formula Cu31S16 that crystallizes with monoclinic
Monoclinic crystal system
In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. They form a rectangular prism with a...
-prismatic symmetry. It is typically massive in form, but does at times develop thin tabular to prismatic crystals. It occurs with other supergene
Supergene (geology)
In ore deposit geology, supergene processes or enrichment occur relatively near the surface. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary sulfide ore minerals and...
minerals such as chalcocite
Chalcocite
Chalcocite, copper sulfide , is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system....
, covellite
Covellite
Covellite is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is ubiquitous in copper ores, it is found in limited abundance and is not an important ore of copper itself, although it is well known to mineral collectors.The mineral is associated with chalcocite in zones...
and digenite
Digenite
Digenite is a copper sulfide mineral with formula: Cu9S5. Digenite is a black to dark blue opaque mineral that crystallizes with a trigonal - hexagonal scalenohedral structure. In habit it is usually massive, but does often show pseudo-cubic forms. It has poor to indistinct cleavage and a brittle...
in the enriched zone of copper ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
bodies. It is a member of the chalcocite group, and very similar to chalcocite, Cu2S, in its composition and properties, but the two minerals can be distinguished from each other by x-ray powder diffraction. Intergrowths and transformations between djurleite, digenite and chalcocite are common. Many of the reported associations of digenite and djurleite, however, identified by powder diffraction, could be anilite and djurleite, as anilite transforms to digenite during grinding.
Djurleite was named for the Swedish chemist Seved Djurle (1918– ), from the University of Uppsala, Sweden, who first synthesized the mineral in 1958, prior to its discovery in nature. The natural material was first described in 1962 by E H Roseboom Jr, of the US Geological Survey, from occurrences at the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
, Barranca del Cobre
Copper Canyon
Copper Canyon is a group of canyons consisting of six distinct canyons in the Sierra Tarahumara in the southwestern part of the state of Chihuahua in Mexico...
, Chihuahua, Mexico.
The chalcocite group
The chalcocite group is a group of closely related copper sulfides, with the formulae:- ChalcociteChalcociteChalcocite, copper sulfide , is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system....
(two polymorphsPolymorphism (materials science)Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...
) Cu2S - Djurleite Cu31S16 (Cu1.94S)
- DigeniteDigeniteDigenite is a copper sulfide mineral with formula: Cu9S5. Digenite is a black to dark blue opaque mineral that crystallizes with a trigonal - hexagonal scalenohedral structure. In habit it is usually massive, but does often show pseudo-cubic forms. It has poor to indistinct cleavage and a brittle...
(Cu1.80S) - Roxbyite (Cu1.78S)
- Anilite Cu7S4 (Cu1.75S)
- GeeriteGeeriteGeerite is a copper sulfide mineral with the chemical formula Cu8S5. The mineral is named after the original collector, Adam Geer, of Utica, New York, USA.-Crystallography:...
Cu8.5S5 (Cu1.70S) - Spionkopite (Cu1.32S)
- CovelliteCovelliteCovellite is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is ubiquitous in copper ores, it is found in limited abundance and is not an important ore of copper itself, although it is well known to mineral collectors.The mineral is associated with chalcocite in zones...
(CuS)
Unit cell
Djurleite has a monoclinicMonoclinic crystal system
In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. They form a rectangular prism with a...
structure with a large unit cell containing 248 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...
and 128 sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
atoms. The formula is Cu31S16, molar mass
Molar mass
Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol...
2483 g, and there are 8 formula units per unit cell (Z = 8).
The crystal class is 2/m, meaning the structure has an axis of twofold rotational symmetry perpendicular to a mirror plane
Reflection symmetry
Reflection symmetry, reflectional symmetry, line symmetry, mirror symmetry, mirror-image symmetry, or bilateral symmetry is symmetry with respect to reflection. That is, a figure which does not change upon undergoing a reflection has reflectional symmetry.In 2D there is a line of symmetry, in 3D a...
. The space group
Space group
In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...
is P21/c, and the unit cell parameters are a = 26.897 Å
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
, b = 15.745 Å, c = 13.565 Å and β = 90.13°. The structure is based on hexagonal closest packing of sulfur atoms with a monoclinic space group.
Physical properties
Crystals are short prismatic and thick tabular, but the mineral usually occurs in a massive and compact form. There is no cleavageCleavage (crystal)
Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the...
. Pseudohexagonal twins
Crystal twinning
Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations. A twin boundary or composition surface separates the two crystals....
are common, with crystal blocks rotated around the a crystal axis
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
, which is normal to the close-packed layers, by multiples of 60o. Djurleite is brittle, with a conchoidal (shell-like) fracture
Fracture (mineralogy)
In the field of mineralogy, fracture is a term used to describe the shape and texture of the surface formed when a mineral is fractured. Minerals often have a highly distinctive fracture, making it a principal feature used in their identification....
. It is a soft mineral, with hardness 2½ to 3, a little less than that of 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:...
. The 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...
, 5.63, is high, due to the copper content, djurleite is denser than the copper-iron sulfide bornite
Bornite
Bornite is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system .-Appearance:Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places...
, but not as dense as the iron-arsenic sulfide arsenopyrite
Arsenopyrite
Arsenopyrite is an iron arsenic sulfide . It is a hard metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases elemental sulfur. When arsenopyrite is heated, it becomes magnetic and gives off toxic fumes...
.
Optical properties
Djurleite is grey, blue-black or black, with a black streakStreak (mineralogy)
The streak of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a more consistent characteristic color, and is thus...
and a submetallic to metallic 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....
. It is an opaque mineral, so refractive indices
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....
are not defined. The reflectivity (the percentage of incident energy which is reflected from a surface) for light of wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
540 nm
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
varies between 29.6 and 30.2, and is slightly dependent on the direction of the incident light, that is to say, the mineral is weakly anisotropic.
Environment
Djurleite is a widely distributed but little known ore mineral of copper, found in the secondary enrichment zonesSupergene (geology)
In ore deposit geology, supergene processes or enrichment occur relatively near the surface. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary sulfide ore minerals and...
of 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...
deposits, associated with other secondary copper sulfides digenite
Digenite
Digenite is a copper sulfide mineral with formula: Cu9S5. Digenite is a black to dark blue opaque mineral that crystallizes with a trigonal - hexagonal scalenohedral structure. In habit it is usually massive, but does often show pseudo-cubic forms. It has poor to indistinct cleavage and a brittle...
, chalcocite
Chalcocite
Chalcocite, copper sulfide , is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system....
, bornite
Bornite
Bornite is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system .-Appearance:Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places...
, chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
and anilite with 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...
.
Occurrence
The type locality is Barranca de Cobre, Chihuahua, Mexico, and the type material is conserved at the Royal Ontario MuseumRoyal Ontario Museum
The Royal Ontario Museum is a museum of world culture and natural history in Toronto, Ontario, Canada. With its main entrance facing Bloor Street in Downtown Toronto, the museum is situated north of Queen's Park and east of Philosopher's Walk in the University of Toronto...
, Toronto, Canada, M25369, and at the National Museum of Natural History
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. Admission is free and the museum is open 364 days a year....
, Washington, DC, USA.