UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven
Ca 2B 5SiO 9(OH) 5Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
MgB 3O 3(OH) 5 · 5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)