About Corundum
Aluminum oxide, an extremely hard mineral second only to diamond. Gem varieties are Ruby (red) and Sapphire (all other colors). Generally, it's a stone of wisdom, strength, ambition, and mental clarity.
Primary Hues
Colorless, Grey, Brown, (Ruby: Red), (Sapphire: Blue, Pink, Yellow, Green, Purple, Orange, etc.)
Geological & Scientific Details
Corundum is classified as a oxide mineral – hematite group mineral which typically crystallizes in the trigonal system. Its chemical formula is Al2O3. Common crystal habits include steep bipyramidal, tabular, prismatic, rhombohedral crystals, massive or granular.
Key Geological Properties:
- Mineral Category: Oxide mineral – Hematite group
- Chemical Formula: Al2O3
- IMA Symbol: Crn[1]
- Crystal System: Trigonal
- Predominant Geological Color: Colorless, gray, golden-brown, brown; purple, pink to red, orange, yellow, green, blue, violet; may be color zoned, asteriated mainly grey and brown
- Crystal Habit: Steep bipyramidal, tabular, prismatic, rhombohedral crystals, massive or granular
- Twinning: Polysynthetic twinning common
- Cleavage: None – parting in 3 directions
- Luster: Adamantine to vitreous
- Streak: Colorless
- Diaphaneity: Transparent, translucent to opaque
Associated Minerals
- Ruby
- Sapphire
- Spinel
- Chrysoberyl
- Garnet
- Kyanite
- Diaspore