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Platinum

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Definition of Platinum

The first documented discovery of platinum was by the Spaniards in the 1500s, in the alluvial gold mines of the Río Pinto, Colombia. They called it platina del Pinto, from platina, which means “little silver,” thinking that it was an impure ore of silver. It was not recognized as a distinct metal until 1735. It is opaque, silvery gray, and markedly dense. Platinum usually occurs as disseminated grains in ironand magnesium-rich igneous rocks and in quartz veins associated with hematite, chlorite, and pyrolusite. When rocks weather, the heavy platinum accumulates as grains and nuggets in the resulting placer deposits. Crystals are rare, but when found they are cubic. Most platinum for commercial use is recovered from primary deposits. Native platinum typically contains iron and metals such as palladium, iridium, and rhodium.

Name: From the Spanish platina, diminutive of plata, silver.

Cell Data: Space Group: Fm3m. a = 3.9231 Z = 4

Chemical Properties of Platinum

Chemical Classification Native
Chemical Composition Pt

Physical Properties of Platinum

Color Steel grey to dark grey
Streak Steel grey to dark grey
Luster Metallic
Cleavage Non
Diaphaneity Opaque
Mohs Hardness 4 – 4½ on Mohs scale
Specific Gravity 14 – 19
Diagnostic Properties Color and metalic luster
Crystal System Cubic
Tenacity Malleable
Fracture Hackly
Density 14 – 19 g/cm3 (Measured)    21.472 g/cm3 (Calculated)

Optical Properties of Platinum

Type Isotropic
Twinning On {111} as interpenetrant contact twins.

Occurrence

Chiefly in placer deposits, or in mafic and ultramafic igneous rocks; rarely in hydrothermal quartz veins or contact metamorphic deposits.

Uses Area

Since ancient times, white gold was used as platinum. The most common use of platinum is usually a catalyst in chemical reactions such as platinum black. Used as jewelry, chemical production and petroleum refining hard drives, medicine and biomedicine, glassmaking equipment, investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.

The standard hydrogen electrode also uses a platinum electrode flattened because of its corrosion resistance and other properties.

Platinum is used as an alloying agent for various metal products including fine wires, non-corrosive laboratory containers, medical instruments, dental prostheses, electrical contacts and thermocouples.

Association

Pt–Fe alloys, chalcopyrite, chromite, magnetite

Distribution

From many deposits world-wide. In the Pinto River, near Papayan, in the Department of Choc´o, Cauca, Colombia [TL]. In the USA, from Platinum Creek, Goodnews Bay, Alaska; in California, in a number of placers, as in Trinity Co.; and at Oroville, Butte Co. In Oregon, at Cape Blanco, Port Orford, Curry Co. In Canada, at Rivi`ere-du-Loup and Rivi`ere des Plantes, Beauce Co., Quebec; in British Columbia, in the Kamloops district, on the Fraser and Tranquille Rivers, and in the Similkameen district, on Granite, Cedar, and Olivine Creeks, tributaries to the Tulameen River; in Alberta, near Edmonton. In Russia, in the Ural Mountains, in a large district surrounding Nizhni Tagil; good crystals from the Konder massif, Aldan Shield, Sakha. In South Africa, at a number of deposits along the Merensky Reef of the Bushveld complex, Transvaal.

References

Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.

Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].

Mindat.org. (2019). Platinum: Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].

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