An apple green crust of Smithsonite on massive dark gray Smithsonite. Locality
- 79 Mine in Arizona
Smithsonite crystals
Smithsonite
crystals from Tsumeb, Namibia
CHEMISTRY - ZnCO3
CRYSTALLOGRAPHY - Hexagonal
CRYSTAL GROWTH AND HABITS - Smithsonite forms rhombohedral crystals that have curved faces or composites. It rarely forms scalenohedral crystals. More commonly it is botryoidal, reniform, or as a crystalline coating or it may be massive.
COLOR AND OPTICAL PROPERTIES - The color of Smithsonite varies from grayish white to dark gray, greenish, brownish, bluish, yellowi, white and even colorless. It is translucent.
HARDNESS - 4 - 4.5
SPECIFIC GRAVITY - 4.0 - 4.4
LUSTER - Vitreous
STREAK - White
BREAKABILITY - Smithsonite has imperfect cleavage along {1011} with uneven to subconchoidal fracture. It is brittle.
OCCURRENCE - Smithsonite is a secondary mineral found in the oxidized zone of zinc bearing mineral veins.
ASSOCIATED MINERALS - Hemimorphite, Cerussite, Malachite, Azurite, Anglesite, Pyromorphite, Mimetite, Aurichalcite, Hydrozincite.
MINERAL NAME - Named in honor of James Smithson, who founded the Smithsonian Institute in Washington D. C.