Gemstones of the world (2001)
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Microcline: KAlSi3O8 Oligoclase: (Na,Ca)Al1-2Si3-2O8
CaBSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references