Grandidierite
Grandidieriet, Grandidierit, Grandidierita, Грандидьерит
Grandidieriet, Grandidierit, Grandidierita, Грандидьерит
Commonly known
rarer (so called collectors stones)
very rare (rarities)
extremely rare (world rarities)
relatively rare organic material
relatively rare organic material
Grandidierite is one of the rarest resp. most expensive gemstones, named after Alfred Grandidier, (1836 - 1912), a French naturalist and explorer on Madagascar.
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Formula:
(Mg,Fe2+)Al3(BO3)(SiO4)O2
Mineral class: silicates Crystal system: orthorhombic Mohs scale: 7.5 Density /g/cm3: 2.99 Cleavage: very good Colors: colorless, greenish, blueish Luster: vitreous Fluorescence: - Pleochroism: X: dark blue to green-blue, Y: colorless, Z: ligth green-blue to dark green Largest faceted, eye-clean Grandidierite: 0.29 ct Deposits: Madagascar ~9 deposits, e.g. Andrahomana / Ranopiso Dep. / Anosy Reg. / Tuléar Prov. / Madagascar (type locality) Antarctica, Germany, Greenland, Norway, Slovakia, South Africa, Surinam, USA Discovery: 1902 1st Description: 1909 History: • Discovery in 1902. • First description in 1909. • Description of the crystal structure in 1968. |
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Andrahomana / Ranopiso Dep. / Anosy Reg. / Tuléar Prov. / Madagascar |
Größere Kartenansicht |
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Grandidierite Mineral
Origin: Andrahomana / Ranopiso Dep. / Anosy Reg. / Tuléar Prov. / Madagascar Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky. |
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Grandidierite Mineral
Origin: Madagascar Photo by kind permission of © www.caltech.edu/, California Institute of Technology. |
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Grandidierite
Weight: 0.19 ct Origin: Fort Dauphin / Madagascar Photo by kind permission of © rock-logic.tripod.com/, Alexandra Woodmansee. |
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