Grandidierite
Blue-green Malagasy borosilicate that only became a gem in 2014.
- Family
- Grandidierite
- Formula
- (Mg,Fe)Al₃(BO₃)(SiO₄)O₂
- Mohs
- 7.5
- System
- Orthorhombic
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Science
Grandidierite is a magnesium iron aluminium borosilicate, strongly trichroic in blue, green and colourless. It was described in 1902 from an opaque pegmatite mineral at Andrahomana. Gem-quality material appeared only in 2014, and the small deposit was quickly worked over.
- Mineral
- Grandidierite
- Formula
- (Mg,Fe)Al₃(BO₃)(SiO₄)O₂
- Crystal system
- Orthorhombic
- Mohs hardness
- 7.5
- Specific gravity
- 2.98 to 2.99
- Refractive index
- 1.590 to 1.623
- Lustre
- Vitreous to pearly
- Colours
- Blue-green, Teal
Composition
(Mg,Fe)Al₃(BO₃)(SiO₄)O₂. Made of Magnesium, Iron, Aluminium, Boron, Silicon, Oxygen.
Origin
- MadagascarTranomaro, since 2014
- Sri Lankasingle pebbles
Filled dots are primary sources
Rarity
Transparent stones were unknown until a 2014 find in southern Madagascar. Clean faceted grandidierite over a carat is among the rarest gems available.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Grandidierite sits at 7.5 on the Mohs scale. It will scratch glass and holds a polish in daily wear.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Throat
- Heart
Element
- Water
Zodiac
- Pisces
Planets
- Neptune
Properties
- Communication
- Compassion
- Perspective
Lore
Named for Alfred Grandidier, the French naturalist who explored and mapped Madagascar in the 1860s and 1870s. A near-colourless 0.29-carat Sri Lankan stone was for decades the only faceted example.
No traditional lore exists; it is a collector's gem with practice associations written in the last decade.
- Gem since2014, Tranomaro, Madagascar.
- TrichroicBlue, green and near colourless along its three axes.