Grandidierite
A variety of Minerals
What is Grandidierite?
Originating from Madagascar, grandidierite was discovered by French explorer Alfred Grandidier in 1902. Grandidierite is highly valued for its striking blue-green color, often compared to the vibrant hues of renowned paraíba tourmaline. Its combination of scarcity and remarkable beauty makes it a prized addition to fine jewelry, fetching high market value. The largest cut specimen currently known to the GIA weighs in at 763.5 carats.
Optical Properties
- Refractive Index
- 1.578-1.639
- Birefringence
- 0.037-0.039
- Pleochroism
- Distinct: greenish blue, colorless, blue-green
- Optical Character
- Biaxial negative
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Grandidierite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Grandidierite Localities Map
See where Grandidierite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
More Images
Quick Facts
Physical Properties
- Color
- Bluish green, greenish blue
- Hardness (Mohs)
- 7.5
- Density
- 2.98 - 2.99 g/cm³
- Streak
- White
- Luster
- Vitreous, Pearly
- Crystal System
- Orthorhombic
Chemical Properties
- Chemical Formula
- (Mg,Fe²⁺)(Al,Fe³⁺)₃(SiO₄)(BO₃)O₂
- Elements
- Al,B,Fe,Mg,O,Si
Identify Grandidierite Instantly
- Snap a photo, get instant results
- 6,700+ rocks, minerals & crystals
- Discover collecting spots near you
Grandidierite FAQs
How do I identify Grandidierite?
Grandidierite can be identified by its hardness of 7.5 on the Mohs scale, Bluish green color, Vitreous, Pearly luster, Orthorhombic crystal system. Look for these key characteristics when examining specimens.
What color is Grandidierite?
Grandidierite typically appears in Bluish green, greenish blue. Color can vary depending on impurities and formation conditions.
How hard is Grandidierite?
Grandidierite has a hardness of 7.5 on the Mohs scale. This makes it a relatively hard mineral suitable for jewelry.
%252FAbenakiite-(ce)-01.jpg&size=small)
