Mineral description : Dumortierite
Dumortierite from Ylämaa area, Finland.
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Dumortierite from Harads.
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| Mineral class | Silicates : Kornerupine group. |
| Chemical formula | Al7(BO3)(SiO4)3O3 |
| Crystal system | Orthorombic. |
| Habitus | Crystals prismatic. Often as columnar, massive or fibrous aggregates. |
| Cleavage | [100] good, [110] indistinct, fracture uneven. |
| Hardness | 8.5 |
| Density | 3.41 |
| Color | Blue, violet, pink or brown. |
| Streak | White. |
| Luster | Vitreous to dull, transparent to translucent. |
| Description | |
| Occurance | In coarse grained acid igneous rocks or pegmatites rich in aluminum. Especially when altered by contact metamorphism. |
| Associates | |
| Notes | Insoluble in acids. Infusable. |
| Locations | A rare mineral in Sweden.
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| To silicate index. |
Mineral group index. |
Main index. |
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Last changed : 1998-09-05