Minerals identify

Know how to recognize them

Alum-(K)

Sulfate mineral

Alum-(K) is a hydrous potassium sulfate mineral with formula KAl(SO4)2·12(H2O). It is the mineral form of potassium alum and is referred to as potassium alum in older sources. It is a member of the alum group.

It occurs as colorless to white, soft isometric crystals and efflorescence coatings. Rare crystals are octahedral in form if occurring as precipitates from neutral water solution, but cubic in form if the solution is alkaline.

It occurs as a precipitate around volcanic fumaroles and solfataras. It also occurs as an alteration in argillaceous sediments or coal beds which contain oxidizing (pyrite). Occurs associated with alunogen, melanterite

Occurrences include Mount Vesuvius , Italy and Alum Cave

Identification

Color of mineral

White

Mohs scale ( mineral hardness )

2
2.5

Density ( specific gravity )

1.453

Luster ( interacts light )

Vitreous

Crystal ( diaphaneity )

Cubic