Minerals identify

Know how to recognize them

Pyrophyllite

Silicate mineral

Pyrophyllite is a phyllosilicate composed of aluminium hydroxide : Al2Si4O10(OH)2. It occurs in two forms (habits ): crystalline folia and compact masses; distinct crystals are not known.

The folia have a pronounced pearly luster , owing to the presence of a perfect cleavage parallel to their surfaces: they are flexible but not elastic, and are usually arranged radially in fan-like or spherical groups. This variety, when heated , exfoliates and swells up to many times its original volume, hence the name pyrophyllite, from the Greek pyros (fire)[clarify in 1829. The color of both varieties is white, pale green, greyish or yellowish; they are very soft (hardness of 1.0 to 1.5) and are greasy to the touch. The specific gravity is 2.65 - 2.85. The two varieties are thus very similar to talc.

Identification

Color of mineral

Brown
Green
Yellow
Grey
White

Mohs scale ( mineral hardness )

1.5
2

The streak

White

Density ( specific gravity )

1.534
1.586
1.596

Luster ( interacts light )

Dull
Pearly

Crystal ( diaphaneity )

Monoclinic