Carbonates: Smithsonite

Composition: ZnCO₃; minor iron and other metals may substitute for iron

Crystal system: Trigonal; typically botryoidal or stalactitic, also granular, earthy and porous
masses

1.9.1 smithsonite Broken Hill NSW Australia

Properties:

• Vitreous lustre
• Various colors, greyish white to darker grey, also green, blue and yellowish brown
• White streak
• Knife scratches easily (Mohs Hardness 4-4.5)
• Very high density
• Three cleavages rarely apparent
• Conchoidal fracture
• Not ferromagnetic
• Does not react with cold dilute hydrochloric acid (HCl); is soluble in warm concentrated
  hydrochloric acid

Occurrence:

Smithsonite occurs with other carbonates, oxides and sulfates in secondary deposits formed above
the water table as a result of the weathering of primary zinc-bearing sulfide ore deposits.

1.9.2 smithsonite Broken Hill NSW Australia

Smithsonite is a local source of zinc.