Native Elements - Most minerals are composed of two or more elements, but a few consist of only one element.
The most abundant of the native metals are gold, silver, copper, and platinum.
Native iron occurs in meteorites, but in the Earth it is combined with other elements. Mercury, lead, tin, and zinc are also metals found in the native, or uncombined, form.
Carbon exists in two native forms; graphite and diamond.
The most common nonmetallic native element is sulphur.
Native Elements: The Native Elements Class
The elements which include over one hundred known minerals are a diverse class when taken as a whole. Most of this diversity, however, is due to the diversity of the Non-metals Subclass. The Metals Subclass and related metal alloys contains metals whose properties are rather similar due to the common way in which they crystallize and bond. The greatest difference in the metals is color. The non-metals, however, are extremely diverse. For instance, the hardest mineral known to man is from this subclass, as well as one of the softest. The non-metals include some elements known as semi-metals who share some properties with metals but differ in other characteristics.
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Native Elements: Antimony
Statistics and Information; Native antimony is found only in samll quantities in hydrothermal veins, where it is formed by reactions of antimony dulphur minerals. As antimony occurs rarley as a native element, the economic sources of this metal are ores, mainly stibnite. The natural sulfide of antimony was known and used in Biblical times as medicine and as a cosmetic. Antimony in its elemental form is a silvery white, brittle crystalline solid that exhibits poor electrical and heat conductivity properties. Commercial forms of antimony are generally ingots, broken pieces, granules, and cast cake. Other forms are powder, shot, and single crystals.
[http://minerals.usgs.gov/]
Native Elements: Arsenic
Arsenic (symbol As, at. no. 33, r.a.m. 74.92) a metalloid in Group 15 of the periodic table; the most common and stable of its allotropes is a grey metallic substance. It reacts with concentrated acids, non-metals, and some metals, forming compounds in which it shows valencies 3 and 5. Arsenic is used in alloys (e.g. lead shot) as a hardening agent; in combination with gallium it is widely used in semiconductor devices. Arsenic is on the border line between metals and nonmetals. Its chemical symbol is As. It occurs in nature chiefly in combination with other minerals. Among the common compounds are arsenopyrite, or mispickel (FeSAs); leucopyrite (FeAs); realgar (As2S2); and orpiment, or king's yellow (As2S3). Arsenic compounds usually appear in metal-bearing ores. Most of the world's supply of white arsenic is recovered as a by-product of the smelting of lead and copper ores. Arsenic does not
often form in its elemental state and is far more common in sulfides and sulfosalts such as arsenopyrite, orpiment, realgar, lollingite and tennantite. Due to the abundance of these arsenic bearing ores and the rarity of native arsenic, it is not an important ore of itself. Native arsenic is found in silver ore veins and is processed along with the silver ore and is therefore is a minor source of arsenic.
[http://www.webmineral.com/]
Native Elements: Bismuth
Bismuth is a semi-metal that occurs rarely as a native element. It is related to arsenic and antimony in structure and has similar physical properties. They are all brittle and are poorer conductors of heat and electricty than metals. Bismuth is not of great economic importance, most of that produced is used for medicines and cosmetics. Bismuth is often used in pharmaceutical and cosmetic products. The chemical element bismuth is a soft, brittle, highly lustrous metal belonging to the same group in the periodic table as arsenic, Group VA. Its symbol is Bi, its atomic number is 83, and its atomic weight is 208.9806. The discoverer of the element is unknown, as is the origin of its name. No record exists of its use in ancient times, but Europeans had become aware of its existence by the Middle Ages
[http://www.webmineral.com/]
Native Elements: Copper
Copper (symbol Cu, at. no. 29, r.a.m. 63.55), a reddish-yellow metallic element which is a good conductor of heat and electricity, and is corrosion-resistant. Copper was the first metal humans used for tools and implements, probably because copper, like gold and silver, is sometimes found in a pure state and can be beaten into shape even when cold. The chief copper ores are the sulfide chalcocite, chemical symbol Cu2S, and the copper-bearing pyrite chalcopyrite, CuFeS2. Other copper ores are covellite, CuS; bornite, Cu5FeS4; enargite, Cu3AsS4; cuprite, Cu2O; and malachite, Cu2(OH)2CO3. Named after the Greek word Kyprios which is the name of the island of Cyprus, which once produced this metal.
[http://www.webmineral.com/]
Native Elements: Diamond
Diamond a crystalline form of pure carbon, the hardest substance known. Formed under intense heat and pressure, often in volcanic conduits at great depth, crystals occur in igneous rocks and in gravels, in regions as far apart as South Africa, Brazil, and Siberia. Colourless diamonds (about 25 per cent of those found) are the hardest and cut cleanest, being highly valued as gemstones. Pure carbon forms one of the softest minerals (graphite) and the hardest natural substance (diamond). Despite diamond's unequalled hardness (resistance to scratching) diamond cleaves (breaks along flat planes) easily when struck sharply. When placed in a flame, diamond will burn completely without leaving an ash. Diamonds stick to grease and cannot be wet with water--a property which is used to separate diamonds from crushed rock and dirt. Industrial diamonds, which are used for abrasives, are sometimes referred
to as bort or carbonado.
[http://webmineral.com/]
Native Elements: Gold
Gold (symbol Au, at. no. 79, r.a.m. 196.97), a soft, yellow, metallic element, one of the transition metals. It is very unreactive, though attacked by halogens and aqua regia. Occurring in nature as small particles of the free metal, in quartz or in alluvium, it caused the 19th-century gold rushes in America and Australia; today it is produced mainly in Russia and South Africa. Veins of gold-bearing ore occur most commonly in cracks and fissures in igneous rock. It is thought that the gold and its associated minerals are precipitated from superheated fluids forced upward from the depths of the Earth. In these hydrothermal deposits, gold is often associated with quartz or various sulfides. Gold is a pleasure to own and possess, as many people have discovered throughout the ages and around the world. Gold is a very stubborn element when it comes to reacting to or combining with other elements.
Keeping this in mind, helps to explain many things about gold. There are very few true gold ores, besides native gold, because it forms a major part of only a few rare minerals, it is found as little more than a trace in a few others or it is alloyed to a small extent with other metals such as silver. Gold is almost indestructible and has been used and then reused for centuries to the extent that all gold of known existence is almost equal to all the gold that has ever been mined. Gold is a great medium metal for jewelry, as it never tarnishes. Native gold wires emerging from massive white quartz can make for a visually stunning specimen.
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Native Elements: Graphite
Graphite like diamond, is a form of pure carbon. The carbon atoms in graphite are joined together in hexagonal arrays in two-dimensional sheets stacked one on top of another. This gives graphite its characteristic basal cleavage and flaking, which imparts a greasy feel and gives it lubricant properties. Graphite is also known as plumbago or black lead. Graphite are mainly formed when sediments rich in organic matter are metamorphosed. Graphite is a polymorph of the element carbon. diamond is another polymorph. The two share the same chemistry, carbon, but have very different structures and very different properties. Diamond is hardest mineral known to man, Graphite is one of the softest. Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity. Diamond is the ultimate abrasive, Graphite is a very good lubricant. Diamond is usually transparent, Graphite is
opaque. Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system.
[http://www.webmineral.com/]
Native Elements: Mercury
Mercury (symbol Hg, at. no. 80, r.a.m. 200.59), a silver-coloured metallic element belonging to Group 12 of the periodic table. Mercury is the only pure metal that is a liquid at room temperature. It is rather unreactive but forms complexes and organomercury compounds; it forms compounds in which it shows valency 2 and a few less stable compounds where its valency is 1. poisonous, silvery-white, slowly tarnishing, liquid metal (sometimes called quicksilver) that does not wet glass or cling to it and is therefore used in thermometers, barometers, manometers, and other scientific instruments. It is the only elemental metal that is liquid at room temperature; it freezes into a soft solid resembling tin or lead at -38o F (-39o C). Mercury is unique, as it is the only metal that is liquid at room temperature, having a melting point of -40 C, and a boiling point of 357 C. This silvery liquid metal
is very dense, yet has a high surface tension that causes is to form tiny little perfect spheres in the pores of the rocks it is found in. Many mineralogical characteristics simply do not apply to a liquid: there is no "hardness", since it cannot be scratched (nor can it scratch); there is no crystal structure, no fracture, no cleavage, no streak; all of course, at room temperatures. When frozen, mercury forms crystals in the rhombohedral system at low pressure, and in the tetragonal system at high pressure.
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Native Elements: Platinum
Platinum (symbol Pt, at. no. 78, r.a.m. 195.09), a silvery-white, very malleable and ductile transition metal long known in South America. Although sparse and therefore precious, it occurs naturally in the form of fine black grains in alluvial deposits of heavy sands and in heavy metal sulphide ores from which it can be readily obtained by reduction. Platinum is found in the fairly pure forms of small grains or nuggets, usually alloyed with other metals of its chemical group--iridium, osmium, palladium, rhodium, or ruthenium. The only platinum compound known to occur in nature is the mineral ore sperrylite, or platinum arsenide. Platinum is also obtained as a by-product of the refining of nickel, gold, silver, and copper ores. Native platinum is an exotic mineral specimen and an expensive metal. Unfortunately, well formed crystals of platinum are very rare and the common habit of platinum is
nuggets and grains. Pure platinum is unknown of in nature as it usually is alloyed with other metals such as iron, copper, gold, nickel, iridium, palladium, rhodium, ruthenium and osmium. The presence of these other metals tends to lower the density of platinum from a pure metal specific gravity of 21.5 to as low as 14 and very rarely any higher than 19 in natural specimens.
[http://webmineral.com/]
Native Elements: Silver
Silver (symbol Ag, at. no. 47, r.a.m. 107.87), a brilliant white, malleable, transition metal. It has the highest known electrical conductivity; and is one of the so-called precious metals. It occurs widely in nature--mostly in South Africa and Russia--both in sulphide ores and as the native or free metal. Silver can be extracted from ores before smelting, by treating with cyanide and then displacing with zinc, or by amalgamating with mercury followed by distillation. Unlike gold, silver is present in many naturally occurring minerals. Some silver is obtained in native form or from such ores as argentite (silver sulfide) or cerargyrite (silver chloride). Silver has been mined for eons and has always been popular in jewelry and for coinage. Only in the past hundred years however, has the demand for silver been so great. The reason for this demand is the use of silver in the photography
industry, which takes advantage of silver's reactivity to light. Native Silver is rare and much silver is produced from silver-bearing minerals such as prousite, pyrargyrite, galena, etc. Specimens of Native Silver usually consist of wires that are curved and intertwined together, making an inspiring mineralogical curiosity.
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Native Elements: Sulphur
Sulphur (US, sulfur; symbol S, at. no. 16, r.a.m. 32.06), a yellow non-metallic element in Group 16 of the periodic table that exists in two different allotropes, both of which are yellow. It occurs naturally both in the free state and in sulphides and sulphates, and is found chiefly around hot springs, and in volcanic regions. Sulfur, which is given a bad reputation because of its odor, can make a very beautiful mineral specimen, and fine quality examples are much sought after. The unmistakable deep yellow color is not matched by any other mineral and the nicely shaped crystal forms of sulfur add to its attractiveness. As for the odor, this occurs when water mixes with the sulfur and a small amount of hydrogen sulfide (H2S) gas is produced. Although only small amounts of H2S form from just moisture in the air, it is a powerful odor producer and is the dominating contributor to the odor of
rotten eggs. Rest assured, though, that most specimens of sulfur, when kept dry, do not emit a strong odor and this is not difficult for collectors of fine sulfur specimens to ensure.
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Native Elements: Introduction
We will begin with the native elements and sulfides because these are relatively easy to understand and they show many of the features that we have been talking about during the crystallography portion of the course.
[http://www.geology.wisc.edu/]
