Bismuth

Physical Properties

Hardness: 2.25 on Mohs scale; Color: Silver-white (inner), Iridescent/Rainbow (surface); Luster: Metallic; Crystal Structure: Trigonal (often hopper-shaped in lab); Specific Gravity: 9.78

Formation & Geological History

Formed in hydrothermal veins or pegmatites; mostly produced as a byproduct of lead and copper refining. The rainbow colors are caused by a thin layer of oxidation (bismuth oxide) that forms as it cools.

Uses & Applications

Used in cosmetics (bismuth oxychloride), pharmaceuticals (Pepto-Bismol), low-melting point alloys, lead-free soldering, and as collector specimens.

Geological Facts

Bismuth is more than twice as dense as iron. Until 2003, it was believed to be stable, but it is actually radioactive with an extremely long half-life (a billion times longer than the age of the universe).

Field Identification & Locations

Identify by its high density, metallic silver-pink fresh surface, and brittle nature. It is naturally rare and most colorful specimens available to collectors are lab-grown.

Identified on: 5/19/2026

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