Grandidierite

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Grandidierite is a greenish blue or bluish green mineral named after French explorer and naturalist Alfred Grandidier. The mineral was originally discovered on the southern coast of Madagascar in the Andrahomana area. A new gem quality deposit was found near Tranomaro, Madagascar in 2014.

Grandidierite Polished
Grandidierite Classification
Common Name Grandidierite
Species Grandidierite
Grandidierite Optical Properties
Transparency Transparent-Translucent
Dispersion Strength: Strong Fire
Refractive Index 1.590-1.639
Birefringence 0.033- 0.037
Optic Character Biaxial
Optic Sign Negative
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism Trichroic, pale yellow to colorless, greenish blue, and blue or greenish blue, blue-green and colorless
Grandidierite Characteristic Physical Properties
Hardness 7-7.5
Streak White
Specific Gravity 2.85-3.010
Toughness Good
Inclusions Apatite, monazite, and zircon crystals, liquid and 2-phase inclusions. Parallel growth planes.
Luster Vitreous
Fracture Uneven
Cleavage Good, Distinct
Grandidierite Chemistry & Crystallography
Chemical Name magnesium aluminum borosilicate
Chemical Formula (Mg,Fe)Al3(BO4)(SiO4)O
Crystal System Orthorhombic
Chemistry Classification Silicate

Grandidierite Colors

  • Blue Grandidierite Blue
  • Green Grandidierite Green

Countries of Origin

Madagascar

Care

Normal care

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Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.