Hardness: 7 - 7.5
Density: 3.0 - 3.2
Streak: White to gray
Lustre: Vitreous, shining-pearly
Habit: Prismatic crystals, very striated faces
Colours: Black, any colour
| ||Crystal System: Hexagonal|
Cleavage: Very indistinct
Reaction with HCl: None
Identification in hand sample:
Columnar crystals and vertical striations are characteristic, also has poor cleavage.
Typical in granitic pegmatites, accessory in granite, granodiorite and related felsic igneous rocks. Also in schist, gneiss, quartzite and phyllite.
Industrial / ecomonic uses:
Gemstone. Due to piezoelectric properties, it is also used in the manufacture of pressure gauges and other electronic components.
Can be a multitude of different colours, depending on the variety.