Platinum

About it

Grey grains and nuggets that do not tarnish, much heavier than silver; iron-rich grains may follow a magnet. Mostly from placers in the Urals, Colombia's Chocó, and Goodnews Bay, Alaska; crystals are rare.

Type

Mineral

Group

Native element, platinum group

Formula

Pt

Hardness (Mohs)

4–4.5

Specific gravity

14–21.5

Streak

steel grey

Lustre

metallic

Crystal system

Isometric (cubic)

Colours

steel grey, silver white

Transparency

opaque

Cleavage and fracture

none; hackly fracture, malleable

Magnetic

Weakly

Typical values: real specimens vary. For more, see mindat.org.