Rhodizite

Crystal system Cubic
Transparency Transparent to translucent
Luster Vitreous to subadamantine
Fracture Conchoidal
Cleavage conchoidal
Specific Gravity 3.40
Hardness 8
Optical Character Single Refractive
Refractive index 1.690
Birefringence
Dispersion
Fluorescence weak yellow
Pleochroism
Chemical Formula KAl2B3O8
Comments
Streak

Rhodizite (ROE-diz-ite) is a very rare mineral that is sometimes cut for collectors. In gem quality it is transparent and ranges from colorless to light yellow and light yellowish green; less commonly, it has been found in a translucent, light-red form. The name of the species comes from the Greek word meaning "to be like a rose", because when a piece of the mineral is subjected to the flame of the blowpipe, a red color is imparted to the flame.

Rhodizite, which is a potassium-aluminum borate (KAl2B3O8 is described as being pseudotetrahedral, so there is some question as to whether it is isometric. Many questions surround this very rare mineral. It is very hard (IP, has a vitreous to subadamantine luster, a specific gravity of 3.40, and an R.I. of 1.69+ Identification should cause no difficulty because of its characteristic R.I. and its isotropic nature. The principal localities for this unusual mineral are near Sverdlovsk, in the Ural Mountains (Russia), and Madagascar.