Grandidierite
![[icon]](/enwiki/wiki/File:Wiki_letter_w_cropped.svg){kind=small} | This section needs expansion. You can help by adding to it. (June 2019) |
| Grandidierite | |
|---|---|
 | |
| General | |
| Category | Nesosilicate |
| Formula (repeating unit) | (Mg,Fe2+)Al3(BO3)(SiO4)O2 |
| Strunz classification | 9.AJ.05 |
| Dana classification | 54.01.01.01 |
| Crystal system | OrthorhombicB |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pbnm |
| Identification | |
| Color | Bluish green |
| Twinning | none |
| Cleavage | Perfect |
| Fracture | Brittle |
| Mohs scale hardness | 7.5 |
| Luster | Vitreous, Pearly |
| Streak | White |
| Diaphaneity | Transparent, Translucent |
| Density | 2.976 |
| Optical properties | Biaxial (-) |
| Refractive index | 1.583 - 1.639 |
| Pleochroism | Visible |
| 2V angle | Measured: 24° to 32°, Calculated: 32° |
| Dispersion | strong r < v |
| References | [1][2] |
Grandidierite is an extremely rare mineral and gem that was first discovered in 1902 in southern Madagascar.[3] The mineral was named in honor of French explorer Alfred Grandidier (1836–1912) who studied the natural history of Madagascar.[1]
Grandidierite is considered one of the rarest and most expensive gemstone in existence which can fetch prices up to $20,000 per carat
| Largest Faceted Grandidierite | Details |
|---|---|
 |
World's Largest Known Cut Grandidierite Owned by Gloman Merritt GIL Report Certificate Number STN201811139168 |
References
- ^ a b Grandidierite: Grandidierite mineral information on Mindat
- ^ Grandidierite mineral data on Webmineral
- ^ "Grandidierite: One of the World's Rarest Gemstones at AJS Gems". www.ajsgem.com. Retrieved 2019-06-15.
 | This article about a specific silicate mineral is a stub. You can help Wikipedia by expanding it. |