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.
Cell Data: Space Group: Fm3m. a = 3.9231 Z = 4
Name: From the Spanish platina, diminutive of plata, silver.
Association: Pt–Fe alloys, chalcopyrite, chromite, magnetite
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.
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].
