Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
111 (perfect in four directions)
{010} perfect; {100} good, interrupted; {101} indistinct; {001} in traces