Dumortierite
Real mineral · uncommon · Al₇(BO₃)(SiO₄)₃O₃
Aluminium boron silicate forming blue to violet fibrous masses in aluminium-rich metamorphic and igneous rocks. Its colour is stable and does not fade. Used as a gemstone and as a ceramic raw material requiring high firing temperatures.
Identity
- Formula
- Al₇(BO₃)(SiO₄)₃O₃
- Chemical class
- silicate
Crystallography
- Crystal system
- orthorhombic
- Habits
- prismatic, massive, fibrous
- Fracture
- subconchoidal
Physical properties
- Mohs hardness
- 7
- Density
- 3.3 g/cm³
- Luster
- vitreous, silky
- Colors
- blue, violet-blue, pink, brown
- Streak
- white
- Transparency
- translucent, opaque
Geology
- Origins
- metamorphic, igneous
- Host rocks
- schist, pegmatite, quartzite
- Associated minerals
- Quartz, feldspar, Tourmaline, Kyanite
- Geography
- France, Madagascar, Namibia, USA, Brazil
Classification
- Rarity
- uncommon
- Gem quality
- Yes
Arcane properties
- Affinity
- arcane, mind
- Effects
- mind, warding
- Planar origin
- Material Plane
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