Platinum

Lore & Background

Platinum does not corrode, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts.

Reader's Guide

Platinum is a key component in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. It is also used in the glass industry to manipulate molten glass, which does not 'wet' platinum. Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy as treatment for certain types of cancer. Because of its scarcity in Earth's crust, barely a few hundred metric tonnes are produced annually, and given its critical and important uses, it is highly valuable as well as a major precious metal commodity.

Did You Know?

• Gold is the most ductile of pure metals, not platinum.
• The most abundant isotope of platinum is 195Pt, comprising 33.83% of all platinum.
• Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia to form chloroplatinic acid.
• The radioactive isotope 190Pt undergoes alpha decay with a half-life of approximately 6.5×10^11 years.

Physical & Chemical Properties

Platinum is a lustrous, silver-white transition metal that stands out for its extraordinary ductility, exceeding even gold, silver, and copper among pure metals. It is dense, malleable, and highly resistant to corrosion, earning its classification as a noble metal. Its most common oxidation states are +2 and +4, with tetracoordinate platinum(II) compounds tending to adopt 16-electron square planar geometries. The metal resists hydrochloric and nitric acids individually but dissolves in hot aqua regia to yield chloroplatinic acid. As a soft acid, the Pt²⁺ ion exhibits a strong affinity for sulfide and sulfur ligands, a property that demands careful solvent selection in synthetic chemistry.

Rarity, Occurrence & Mining

Platinum is extraordinarily scarce in Earth's crust, occurring at a concentration of only about 5 micrograms per kilogram. This extreme rarity means barely a few hundred metric tonnes are produced globally each year, yet the metal's critical uses make it a highly valuable precious commodity. It is often found chemically uncombined as native platinum, particularly in alluvial river sands. Pre-Columbian South American natives in Colombia's Chocó Department worked these deposits into artifacts long before European contact. Major geological sources include the Ural Mountains in Russia and the Sudbury Basin in Ontario, Canada, where the arsenide mineral sperrylite (PtAs₂) serves as a key platinum-bearing phase in nickel ores. In nickel and copper deposits, platinum-group metals also occur as sulfides, tellurides, antimonides, and end alloys.

Industrial & Medical Applications

Platinum's chemical inertness and resistance to wear make it indispensable across a remarkable range of industries. Beyond catalysis, platinum appears in laboratory equipment, electrical contacts, electrodes, platinum resistance thermometers, and dentistry. In the glass industry, molten glass does not wet platinum, making the metal ideal for manipulating it. Its resistance to tarnish and wear suits fine jewelry perfectly. Perhaps most remarkably, platinum compounds such as cisplatin, oxaliplatin, and carboplatin serve as chemotherapy agents in the treatment of certain cancers, bridging the gap between inorganic chemistry and life-saving medicine. This versatility, spanning from automotive exhaust systems to oncology wards, underscores why such a scarce element commands such a premium price.

History & Scientific Recognition

Although pre-Columbian South American peoples crafted artifacts from platinum found in alluvial sands, European awareness of the metal remained limited to passing references in 16th-century writings. The element's name derives from the Spanish platina, a diminutive of plata (silver), reflecting its silvery-white appearance. In the modern era, platinum's scientific importance has grown considerably. The element's six naturally occurring isotopes, including the NMR-active ¹⁹⁵Pt with its non-zero nuclear spin, have provided valuable tools in spectroscopy and isotope geology. Together, these contributions cement platinum's dual role as both a practical industrial material and a subject of fundamental scientific inquiry.