Hisingerite

Occurs in Pinal County.

Chemical Formula: Fe₃+2(Si₂O₅)(OH)₄·2H₂O

Specific Gravity: 3.1

Luster: Earthy

Hardness: 1.5-2.5

Hisingerite is a hydrated iron silicate mineral that often appears as brownish-black to brown masses or crusts. It is found in iron ore deposits.

Next Pinal County mineral: Hollandite