About Ottrelite
A manganese iron magnesium aluminum silicate hydroxide, part of the Chloritoid group, typically dark green to black. It's a grounding stone associated with emotional stability and Earth connection.
Primary Hues
Greyish-Green, Greenish-Black, Black, often forms small platy crystals
Geological & Scientific Details
Ottrelite is classified as a nesosilicate mineral. Its chemical formula is (Mn,Fe,Mg)2Al4Si2O10(OH)4. Common crystal habits include granular.
Key Geological Properties:
- Mineral Category: Nesosilicate
- Chemical Formula: (Mn,Fe,Mg)2Al4Si2O10(OH)4
- Formula Mass (g/mol): 490.11
- Predominant Geological Color: Pistachio green
- Crystal Habit: Granular
- Twinning: Polysynthetic, {001}
- Cleavage: {001} perfect; {110} likely
- Luster: Vitreous to nearly adamantine on cleavages
- Streak: Greenish, grayish
- Diaphaneity: Translucent
Associated Minerals
- Chloritoid (forms series with)
- Garnet
- Staurolite
- Kyanite
- Muscovite (common in low to medium-grade metamorphic schists)