Axinite
Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate,. Axinite is pyroelectric and piezoelectric.
The axinite group includes:
- Axinite- or ferroaxinite, Ca2Fe2+Al2BOSi4O15 iron rich, clove-brown, brown, plum-blue, pearl-gray
- Axinite- or magnesioaxinite, Ca2MgAl2BOSi4O15 magnesium rich, pale blue to pale violet; light brown to light pink
- Axinite- or manganaxinite, Ca2Mn2+Al2BOSi4O15 manganese rich, honey-yellow, clove-brown, brown to blue
- Tinzenite 3Al2BOSi4O15 iron – manganese intermediate, yellow, brownish yellow-green