Gems, Conchoidal, Brittle
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Ca 3Ti4+2(Fe3+2Si)O 12Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Na 4AlBeSi 4O 12ClMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references