Pyrophyllite is a phyllosilicate mineral and composed of aluminium silicate hydroxide: AlSi2O5OH. It is an early stage metamorphic mineral and is found as a constituent of slate, phyllite, some schists and other early stage metamorphic rocks. Pyrophyllite belongs to the montmorillonite group of minerals. It is remarkably similar to talc, which belongs to the same mineral family, except that magnesium is substituted for aluminium.
PHYSICAL PROPERTIES :
Color is usually white, colorless, gray, yellow, pale green and/or blue. It can also be stained brown by iron oxides.
Luster is greasy to dull, but pearly on cleavage surfaces.
Transparency: Crystals are mostly translucent to opaque.
Cleavage is perfect in one direction.
Hardness is 1 – 1.5 (soft enough to be scratched by a fingernail).
Specific Gravity is approximately 2.65 – 2.85 (average).
Uses :
The compact variety of pyrophyllite is used for slate pencils and tailors chalk
It is added to clay to reduce thermal expansion when firing
For manufacturing bricks.
For manufacturing insectisides & pesticides.
Used as a filler in Detergents.
Used as a filler in Industrial Paints.
Mixed with other minerals in manufacturing tiles.
As a machinable ceramic material used for electrical resistors, transducer cores, high vacuum gaskets and insulators in electron microscopes.
For carving statues and ornaments owing to its relative ease of machinability
