Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Splintery
None, but may exhibit slight parting
{100} Distinct, {110} Distinct
MgAl2O4
Na 4Al 3Si 9O 24Cl to Ca 4Al 6Si 6O 24(CO 3,SO 4)Walter Schumann , Gemstones of the world (2001) More from other references