Muscovite KAl2(Si3Al)O10(OH)2 Pearly Luster Light is reflected from the thin transparent co-planar sheets of the mica giving them a pearl-like luster Size: 8 cm Arsenopyrite FeAsS Metallic Luster Granular, massive aggregate with a typical reflective luster of polished metal Size: 15 cm Quartz SiO2 Vitreous Luster A glassy luster diagnostic for Quartz Size: 33 cm Quartz SiO2 Vitreous Luster A glassy luster diagnostic for Quartz, here in association with the metallic luster of pyrite Size: 9 cm