Arsenopyrite

FeAsS

This specimen of arsenopyrite displays a dark, blocky habit with a dull metallic luster, showing some visible crystal faces and a brownish-gray tarnish.

Arsenopyrite Physical Properties

Mohs Hardness

5.5

Crystal System

monoclinic

Luster

metallic

Streak Color

dark grayish-black

Cleavage

distinct on {101}

Fracture

uneven to conchoidal

Specific Gravity

6.1

Colors

silvery white, steel gray, tarnished bronze

Transparency

opaque

Type Locality

Widespread in many ore deposits globally

Mineral Group

sulfides

Uses

ore of arsenic, minor ore of gold, collector

Associated Minerals

gold, pyrite, chalcopyrite, sphalerite, galena, quartz

Rarity

common

Geological Context

Arsenopyrite commonly forms in high-temperature hydrothermal veins, contact metamorphic deposits, and some metamorphic rocks, often found alongside other sulfide minerals and gold.

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