• Silicate minerals contain silicon (Si) and oxygen (O), the two most abundant elements in the earth’s crust.
• Over 90% of the common rock-forming minerals are silicates.
• Common silicate minerals include: olivine, pyroxene, amphibole, biotite mica, muscovite mica, plagioclase feldspar, orthoclase feldspar, and quartz.
• The composition of olivine is (Mg,Fe)2SiO4
• Olivine is identified by its glassy luster, conchoidal fracture, and olive-green color.
• Its hardness is 6.5.
• Its specific gravity is 3.2.
Olivine (Photograph by Parvinder Sethi)