Phlogopite

Occurs in Pinal County.

Chemical Formula: KMg₃(AlSi₃O₁₀)(OH)₂

Specific Gravity: 2.7-3.1

Luster: Vitreous to pearly

Hardness: 2.5-3

Phlogopite is a potassium magnesium aluminum silicate mineral that is a member of the mica group. It often forms brown, yellow-brown, or greenish-brown sheets or flakes.

Next Pinal County mineral: Phoenicohroite