Ruby Kyanite Tumbled

Kyanite is rich in Aluminium and is typically blue colour but rare virements can be found in orange, black, white or green. 
This stone forms in sharp bladelike shapes.
Its name comes from the same origin as the colour cyan, being derived from the Ancient Greek word κύανος.
It can be found mainly in Brazil and Africa.
Other names for this mineral are disthene or cyanite.