PLATINUM MINERAL FACTS Nevada Turquoise gem stones
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Platinum Mineral Facts:

Chemical Formula: Pt

Colors: Steel-gray with a bright metallic shine.
The color of platinum is a little more gray than that of silver. Its streak is also gray.

Hardness: 4 to 4.5
unusually high for a metal.

Density: 14 to 19 depending on impurities

Cleavage: None

Crystallography: Isometric
Usually found in small grains or scales. Sometimes in irregular masses and nuggets of larger size. Crystals very rare and commonly distorted.

Luster:. Bright metallic luster.

Optics: (Refractive Index):  Opaque

Platinum Nugget, California










Platinum Nugget, California

Composition, Structure and Associated Minerals:
Platinum is a rare metal which occurs almost exclusively native (only one rare compound, sperrylite, PtAs2 , being known). Platinum is usually alloyed with several per cent of iron and with smaller amounts of iridium, osmium, etc. The amount of metallic platinum present seldom exceeds 80 per cent. Though the metal occurs usually in grains and plates, nevertheless its crystals are sometimes found. On them cubic faces are the most prominent ones, though the octahedrons, the dodecahedrons and tetrahexahedrons have also been identified. Like the crystals of silver and gold, those of platinum are frequently distorted.

Identification and Diagnostics
It is malleable and ductile, a good conductor of electricity, and it is infusible before the blowpipe except in very fine wire. Its melting temperature is 1755. Platinum is unattacked by any single acid, though soluble, like gold, in a mixture of hydrochloric and nitric acids (aqua regia).

Occurrence, Localities and Origins:
Platinum is found in quantity in only a few localities, and 80% of the world's current production comes from South Africa. The largest known primary reserves are in the Bushveld complex in South Africa, and the large copper–nickel deposits near Norilsk in Russia, and the Sudbury Basin of Canada with its large ore deposits are the two other large deposits. In the Sudbury Basin mines the huge quantities of nickel ore processed makes up for the fact that platinum is present as only 0.5 ppm in the ore. Smaller reserves can be found in the United States, at the Stillwater mine in Montana.

It occurs also in the stream sands, as placer deposits, where it has been preserved on account of its great weight and hardness. Platinum alluvial deposits are associated with the rarer metals of the Platinum Group, gold, iron-nickel alloys, chromite, etc. Its original source is probably usually in peridotite rocks or the serpentine rocks resulting from their metamorphism. It occurs so sparingly disseminated through such rocks, however, that it is only after their disintegration and the subsequent concentration of the platinum in the resulting sands that workable deposits of the metal are formed. Placer deposits of platinum are therefore to be looked for in the vicinity of masses of such peridotite rocks.

Historically, before the hard rock supplies came on line, nearly the entire world's supply of platinum came from the Ural Mountains in Russia. The central and northern end of this range has large masses of altered peridotite rocks, and in the sands of the streams descending from it, chiefly on the eastern slope in Siberia, platinum is found in considerable quantity. The chief districts are Nizhni Tagilsk, Bissersk and Goroblagodat, and farther to the north, Bogoslowsk.  Platinum was first discovered in Colombia, South America, where it received its name platina from plata (silver). It is to be found there in two districts near the Pacific coast. The chief district covers the greater part of the intendencia of Choco, while the second, that of Barbacoas, is in the department of Cauca. The platinum occurs here with gold in placer deposits, and, while the fields are not largely productive at present, they may become so. The only platinum found in the United States came from the gold placer deposits of Alaska, Oregon and California.

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Platinum Crystals, Natural, Russian

Natural Platinum Crystals

Natural Platinum Nugget, Russia



Please note that the author, Chris Ralph, retains all copyrights to this entire document and it may not be reproduced, quoted or copied without permission.

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