Native Metal
Encyclopedia
A native metal is any metal
that is found in its metallic form, either pure or as an alloy
, in nature. Metals that can be found as native deposits singly and/or in alloys include aluminium
, antimony
, arsenic
, bismuth
, cadmium
, chromium
, cobalt
, indium
, iron
, nickel
, selenium
, tantalum
, tellurium, tin
, titanium
, and zinc
, as well as two groups of metals: the gold group, and the platinum group
. The gold group consists of gold
, copper
, lead
, aluminium
, mercury
, and silver
. The platinum group consists of platinum
, iridium
, osmium
, palladium
, rhodium
, and ruthenium
.
Only gold, silver, copper and the platinum metals occur in nature in larger amounts. Over geological time scales, very few metals can resist natural weathering processes like oxidation, which is why generally only the less reactive
metals such as gold and platinum are found as native metals. The others usually occur as isolated pockets where a natural chemical process reduces a common compound or ore of the metal, leaving the pure metal behind as small flakes or inclusions.
Non-metallic elements occurring in the native state include carbon
and sulfur
. Silicon
, a semi-metal, has been found in the native state on rare occasions as small inclusions in gold.
Native metals were prehistoric man's only access to metal, since the process of extracting metals from their ores, smelting
, is thought to have been discovered around 6500 BC. However, they could be found only in relatively small amounts, so they could not be used extensively. So while copper and iron were known well before the copper age
and Iron Age
, they would not have a large impact on humankind until the technology to smelt them from their ores, and thus mass produce them appeared.
, which is a method of separating flakes of pure gold from river sediments due to their great density
.
. Typically occurs with silver sulfides and sulfosalts. Various amalgams
of silver and mercury or other metals and mercury do occur rarely as minerals in nature. An example is the mineral eugenite (Ag11Hg2) and related forms.
(Os,Ir,Ru), rutheniridosmine (Ir,Os,Ru), ruthenium
(Ru,Ir), palladium
(Pd,Pt), platinum
Pt, and rhodium
(Rh,Pt). In addition gold, copper and iron occur in these alloys.
has been historically mined as an early source of the metal.
The term Old Copper Complex
is used to describe an ancient North American civilization that utilized native copper deposits for weapons, tools, and decorative objects. This society existed around Lake Superior
, where they found sources of native copper and mined them between 6000 and 3000 BC. Copper would have been especially useful to ancient man as it was much stronger than gold, hard enough to be made into useful items such as fishhooks and woodworking tools, but still soft enough to be easily shaped, unlike meteoric iron.
The same deposits of native copper on the Keweenaw Peninsula
and Isle Royale
were later mined commercially
. From 1845 until 1887, the Michigan Copper Country
was the leading producer of copper in the United States. Masses of native copper weighing hundreds of tons were sometimes found in the mines.
that formed millions of years ago but were preserved from chemical attack by the vacuum of space, and fell to the earth a relatively short time ago. Metallic meteorites are composed primarily of the nickel
-iron
alloy
s: taenite
- high nickel content, and kamacite
- low nickel content. However, there are a very few areas on earth where truly native iron can be found.
Native nickel has been described in serpentinite
due to hydrothermal alteration of ultramafic rocks in New Caledonia
and elsewhere.
Metallic cobalt
has been reported in the Canadian Lorraine Mine, Cobalt-Gowganda region, the Timiskaming District, Ontario
, Canada, and in the Aidyrlya gold deposit in Orenburgskaya Oblast
of the Southern Urals.
For example metallic cadmium
was only found at two locations. One place where metallic cadmium can be found is the Vilyuy River basin in Siberia
. Native molybdenum
has been found in lunar regolith and in the Koryakskii volcano
in Kamchatka Oblast
of Russia.
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
that is found in its metallic form, either pure or as an alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
, in nature. Metals that can be found as native deposits singly and/or in alloys include 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....
, antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...
, arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
, bismuth
Bismuth
Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent poor metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead...
, cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
, 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...
, cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
, indium
Indium
Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...
, 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...
, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
, tantalum
Tantalum
Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...
, tellurium, tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
, 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 zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, as well as two groups of metals: the gold group, and the platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...
. The gold group consists of 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...
, 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...
, lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, 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....
, mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
, and silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
. The platinum group consists of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
, iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
, osmium
Osmium
Osmium is a chemical element with the symbol Os and atomic number 76. Osmium is a hard, brittle, blue-gray or blue-blacktransition metal in the platinum family, and is the densest natural element. Osmium is twice as dense as lead. The density of osmium is , slightly greater than that of iridium,...
, palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
, rhodium
Rhodium
Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...
, and ruthenium
Ruthenium
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russian scientist Karl Ernst Claus discovered the element...
.
Only gold, silver, copper and the platinum metals occur in nature in larger amounts. Over geological time scales, very few metals can resist natural weathering processes like oxidation, which is why generally only the less reactive
Reactive
Reactive may refer to:*Generally, capable of having a reaction*Reactance , the imaginary component of AC impedance*Reactive mind*Reactive programming...
metals such as gold and platinum are found as native metals. The others usually occur as isolated pockets where a natural chemical process reduces a common compound or ore of the metal, leaving the pure metal behind as small flakes or inclusions.
Non-metallic elements occurring in the native state include carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and 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...
. Silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
, a semi-metal, has been found in the native state on rare occasions as small inclusions in gold.
Native metals were prehistoric man's only access to metal, since the process of extracting metals from their ores, smelting
Smelting
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...
, is thought to have been discovered around 6500 BC. However, they could be found only in relatively small amounts, so they could not be used extensively. So while copper and iron were known well before the copper age
Copper Age
The Chalcolithic |stone]]") period or Copper Age, also known as the Eneolithic/Æneolithic , is a phase of the Bronze Age in which the addition of tin to copper to form bronze during smelting remained yet unknown by the metallurgists of the times...
and Iron Age
Iron Age
The Iron Age is the archaeological period generally occurring after the Bronze Age, marked by the prevalent use of iron. The early period of the age is characterized by the widespread use of iron or steel. The adoption of such material coincided with other changes in society, including differing...
, they would not have a large impact on humankind until the technology to smelt them from their ores, and thus mass produce them appeared.
Gold
Gold is the most well known of the native metals. Mined gold is almost invariably portrayed as solid nuggets or veins. Indeed, most gold is mined as native metal and can be found as nuggets, veins or wires of gold in a rock matrix, or fine grains of gold, mixed in with sediments or bound within rock. The iconic image of gold mining for many is gold panningPlacer mining
Placer mining is the mining of alluvial deposits for minerals. This may be done by open-pit or by various surface excavating equipment or tunneling equipment....
, which is a method of separating flakes of pure gold from river sediments due to their great density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
.
Silver
Native silver occurs as rare cubic, octahedral, or dodecahedral crystals. It more commonly as elongated dendritic silver wires or as coatings or massive. It may occur alloyed with gold as electrumElectrum
Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. It has also been produced artificially. The ancient Greeks called it 'gold' or 'white gold', as opposed to 'refined gold'. Its color ranges from pale to bright yellow, depending on the...
. Typically occurs with silver sulfides and sulfosalts. Various amalgams
Amalgam (chemistry)
An amalgam is a substance formed by the reaction of mercury with another metal. Almost all metals can form amalgams with mercury, notable exceptions being iron and platinum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore.The...
of silver and mercury or other metals and mercury do occur rarely as minerals in nature. An example is the mineral eugenite (Ag11Hg2) and related forms.
Platinum group
Natural alloys of the platinum group metals include: native osmiumOsmium
Osmium is a chemical element with the symbol Os and atomic number 76. Osmium is a hard, brittle, blue-gray or blue-blacktransition metal in the platinum family, and is the densest natural element. Osmium is twice as dense as lead. The density of osmium is , slightly greater than that of iridium,...
(Os,Ir,Ru), rutheniridosmine (Ir,Os,Ru), ruthenium
Ruthenium
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russian scientist Karl Ernst Claus discovered the element...
(Ru,Ir), palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
(Pd,Pt), platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
Pt, and rhodium
Rhodium
Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...
(Rh,Pt). In addition gold, copper and iron occur in these alloys.
Copper
Native copperNative copper
Copper, as native copper, is one of the few metallic elements to occur in uncombined form as a natural mineral, although most commonly occurs in oxidized states and mixed with other elements...
has been historically mined as an early source of the metal.
The term Old Copper Complex
Old Copper Complex
Old Copper Complex is a term used for ancient Native North American societies known to have been heavily involved in the utilization of copper for weaponry and tools. It is to be distinguished from the Copper Age , when copper use becomes systematic.The Old Copper Complex of the Western Great Lakes...
is used to describe an ancient North American civilization that utilized native copper deposits for weapons, tools, and decorative objects. This society existed around Lake Superior
Lake Superior
Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...
, where they found sources of native copper and mined them between 6000 and 3000 BC. Copper would have been especially useful to ancient man as it was much stronger than gold, hard enough to be made into useful items such as fishhooks and woodworking tools, but still soft enough to be easily shaped, unlike meteoric iron.
The same deposits of native copper on the Keweenaw Peninsula
Keweenaw Peninsula
The Keweenaw Peninsula is the northern-most part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States. As of the 2000 census, its population was roughly 43,200...
and Isle Royale
Isle Royale
Isle Royale is an island of the Great Lakes, located in the northwest of Lake Superior, and part of the state of Michigan. The island and the 450 surrounding smaller islands and waters make up Isle Royale National Park....
were later mined commercially
Copper mining in Michigan
While it originated thousands of years earlier, copper mining in Michigan became an important industry in the 19th and early 20th centuries. Its rise marked the start of copper mining as a major industry in the United States.-Geology:...
. From 1845 until 1887, the Michigan Copper Country
Copper Country
The Copper Country is an area in the Upper Peninsula of Michigan in the United States, including all of Keweenaw County, Michigan and most of Houghton, Baraga and Ontonagon counties. The area is so named as copper mining was prevalent there from 1845 until the late 1960s, with one mine ...
was the leading producer of copper in the United States. Masses of native copper weighing hundreds of tons were sometimes found in the mines.
Iron, nickel and cobalt
Most of the native iron on earth is actually not in fact "native", in the traditional sense, to earth. It mainly comes from iron-nickel meteoritesIron meteorite
Iron meteorites are meteorites that consist overwhelmingly of nickel-iron alloys. The metal taken from these meteorites is known as meteoric iron and was one of the earliest sources of usable iron available to humans.-Occurrence:...
that formed millions of years ago but were preserved from chemical attack by the vacuum of space, and fell to the earth a relatively short time ago. Metallic meteorites are composed primarily of the nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
-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...
alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
s: taenite
Taenite
Taenite is a mineral found naturally on Earth mostly in iron meteorites. It is an alloy of iron and nickel, with nickel proportions of 20% up to 65%.The name is derived from the Greek for "band". Taenite is a major constituent of iron meteorites...
- high nickel content, and kamacite
Kamacite
Kamacite is a mineral. It is an alloy of iron and nickel, usually in the proportions of 90:10 to 95:5 although impurities such as cobalt or carbon may be present. On the surface of Earth, it occurs naturally only in meteorites. It has a metallic luster, is gray and has no clear cleavage although...
- low nickel content. However, there are a very few areas on earth where truly native iron can be found.
Native nickel has been described in serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...
due to hydrothermal alteration of ultramafic rocks in New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
and elsewhere.
Metallic cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
has been reported in the Canadian Lorraine Mine, Cobalt-Gowganda region, the Timiskaming District, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
, Canada, and in the Aidyrlya gold deposit in Orenburgskaya Oblast
Orenburg Oblast
Orenburg Oblast is a federal subject of Russia . Its administrative center is the city of Orenburg. From 1938 to 1957, it bore the name Chkalov Oblast in honor of Valery Chkalov...
of the Southern Urals.
Others
All other native metals occur only in small quantities or are found in geologically special regions.For example metallic cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
was only found at two locations. One place where metallic cadmium can be found is the Vilyuy River basin in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
. Native molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
has been found in lunar regolith and in the Koryakskii volcano
Koryaksky
Koryaksky or Koryakskaya Sopka is a volcano on the Kamchatka Peninsula in the far east of Russia. It lies within sight of Kamchatka Krai's administrative center, Petropavlovsk-Kamchatsky...
in Kamchatka Oblast
Kamchatka Oblast
Kamchatka Oblast was, until being incorporated into Kamchatka Krai on July 1, 2007, a federal subject of Russia . To the north, it bordered Magadan Oblast and Chukotka Autonomous Okrug. Koryak Autonomous Okrug was located in the northern part of the oblast...
of Russia.