Mineral Of The Day

Mineral Of The Day #115: Pyrophyllite

Mohs Hardness Scale: 1.5-2
Category: Phyllosilicate mineral

Formula: Al₂Si₄O₁₀(OH)₂

Fun Facts:

• Pyrophyllite’s name comes from the Greek pyros (fire) and phyllos (a leaf).
• It has a pronounced pearly lustre.
• The compact variety of pyrophyllite is used for slate pencils and tailors chalk, and is carved by the Chinese into small ornaments.
• Because it has excellent thermal stability, it is added to clay to reduce thermal expansion when firing.
• It is also used as an insecticide and for making bricks.