This is not a terribly attractive gemstone, but faceted gems would be a tremendous rarity. The material is quite brittle, but there is no cleavage to cause problems in cutting. I do not know of the existence of a faceted gem at this writing.
Streak: Greenish gray.
Optics: a = 1.77-1.78; γ= 1.78-1.82.
Biaxial ( + ), 2V = 85°. Usually metamict and amorphous, hence isotropic.
Occurrence: Granites and granite pegmatites. Colorado; Texas; Arizona.
Greenland; Sweden; Norway; USSR; Japan; Switzerland; Australia.
Comments: This is not a terribly attractive gemstone, but faceted gems would be a tremendous rarity. The material is quite brittle, but there is no cleavage to cause problems in cutting. I do not know of the existence of a faceted gem at this writing.
Name: After the Swedish chemist, J. Gadolin.