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Norbergite | Chondrodite | Humite | Clinohumite | |
---|---|---|---|---|
Name Origin | named after the locality at Norberg, Sweden, where it was found |
the name is derived from Greek Chondros meaning grain, due to the granular nature of the mineral |
named after Sir Abraham Hume (1749-1838) an English mineralogist and collector |
|
Chemical Formula | Mg(OH,F)2 . Mg2(SiO4) | Mg(OH,F)2 . 2Mg2(SiO4) | Mg(OH,F)2 . 3Mg2(SiO4) | Mg(OH,F)2 . 4Mg2(SiO4) |
Color | Yellowish tan | Yellow, brown, and red | Yello, deep orange | Yellow, brown, white |
Hardness | 6.5 | 6.5 | 6 | 6 |
Crystal System | orthorhombic | monoclinic | orthorhombic | monoclinic |
Cleavage | poor, Uneven to subconchoidal fracture | |||
Specific Gravity (SG) | 3.15-3.18 | 3.16-3.26 | 3.20-3.32 | 3.17-3.35 |
Luster | Vitreous | |||
Main Sources | Finland, Italy, Spain, Sweden, United States (New York) | |||
Stone Size | Cut humites are always small, generally in the 1-3 carat range. Crystals tend to be dark and filled with inclusions and fractures and large cut gems are very rare. |
Note: Faceted chondrodite, norbergite, and humite is almost unknown, a pity since the color is very rich and the material is hard and durable enough to wear. However, clinohumite crystals from Pamir Mountains occur in sizes allowing the production of gems.
Photo Credit: www.shutterstone.com
References: Color Encyclopedia of Gemstones, Joel E. Arem, VNR publications, New York.
References: Color Encyclopedia of Gemstones, Joel E. Arem, VNR publications, New York.