Hanksite
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Hanksite is a sulfate mineral, distinguished as one of only a handful that contain both carbonate and sulfate ions. It has the chemical formula Na₂₂K(SO₄)₉(CO₃)₂Cl. Wikipedia
Crystal habit: Occurs as short prismatic to tabular hexagonal crystals
Cleavage: Good on
Color: Colorless to pale yellow, may be grayish green due to clay inclusions
Crystal class: Dipyramidal (6/m); H–M symbol: (6/m)
Crystal system: Hexagonal
Formula (repeating unit): Na22K(SO4)9(CO3)2Cl
Luster: Vitreous to dull