Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Uneven, Gems, Sixth Edition (2006)
111 (perfect in four directions)
From the Greek for oblique and fracture, descriptive of the cleavage
C
(Na,K)AlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)