Crystal Bismuth

Chemical Formula

Bi

Composition

Bismuth, usually with traces of arsenic, antimony, and sulfur

Variable Formula

(Bi,As,Sb,S)

Color

Silver-white, sometimes with reddish hue. Oxidizes yellowish to dark gray.

Streak

Silver-white

Hardness

2 - 2.5

Crystal System

Hexagonal

Crystal Forms 
and Aggregates

Crystals, which are uncommon, are usually flat hexagons occurring in parallel groupings. Bismuth also occurs massive and as waterworn nugget in stream beds. Pseudocubic, hopper-like crystal groupings are almost never found in nature, but are laboratory-produced.

Transparency

Opaque

Specific Gravity

9.7 - 9.8

Luster

Metallic

Cleavage

2,1 - prismatic ; 3,1 - basal

Fracture

Hackly to uneven

Tenacity

Brittle and slightly sectile

Other ID Marks

1) Tarnishes yellow to dark gray. 
2) Crystals often striated on cleaved surfaces.

Complex Tests

Becomes slightly malleable when heated, expands when solidifying, and is strongly diamagnetic.

In Group

Native Elements; Semi-Metallic Elements

Striking Features

Color, tarnish, sectility, and striations on cleaved surfaces.

Environment

In mesothermal veins, in hydrothermal replacement deposits, and in granite pegmatites.

Rock Type

Igneous, Metamorphic

Popularity (1-4)

2

Prevalence (1-3)

1

Demand (1-3)

2