About Sillimanite
Aluminum silicate, a polymorph of kyanite and andalusite, often forming fibrous (Fibrolite) or prismatic crystals. It's a stone of focus, leadership, and spiritual connection, enhancing self-discipline and clarity.
Primary Hues
Colorless, White, Grey, Yellow, Brown, Green, Blue, Violet, often forms long, slender prismatic crystals or fibrous masses
Geological & Scientific Details
Sillimanite is classified as a nesosilicate mineral which typically crystallizes in the orthorhombic system. Its chemical formula is Al2SiO5. Common crystal habits include prismatic crystals, fibrous, acicular.
Key Geological Properties:
- Mineral Category: Nesosilicate
- Chemical Formula: Al2SiO5
- IMA Symbol: Sil[1]
- Crystal System: Orthorhombic
- Predominant Geological Color: Colourless or white to grey, also brown, yellow, yellow-green, grey-green, blue-green, blue; colourless in thin section
- Crystal Habit: Prismatic crystals, fibrous, acicular
- Cleavage: {010} perfect
- Luster: Vitreous to subadamantine, silky
- Streak: White
- Diaphaneity: Transparent to translucent
Associated Minerals
- Andalusite
- Kyanite
- Garnet
- Cordierite
- Biotite
- Muscovite
- Quartz
- Feldspar