Garnet’s industrial uses are one of the reasons garnet mining is booming. Garnet has become a bona fide industrial commodity because it is a nearly perfect industrial abrasive. In just the past 15 years, annual world mine production has quadrupled to 1.2 million metric tons of refined garnet concentrate worth $340 million dollars.
The word “garnet” refers to a group of complex silicate minerals with similar crystalline structures but diverse chemical compositions. Garnet’s general chemical formula is A3B2(SiO4)3, with “A” representing such divalent metallic ions as calcium, magnesium, ferrous iron, and manganese, and “B” representing trivalent ions like aluminum, chromium, ferric iron, and manganese. In certain rare garnets, the “B” cation can also include vanadium, titanium, or zirconium ions.
Many of the 14 garnet-group members form mutual solid-solution series. The most familiar and abundant of these garnet minerals are almandine, pyrope, spessartine, grossular, andradite and uvarovite. Garnet-group members vary widely in color, but only slightly in hardness, density, and index of refraction.
Garnet crystallizes in the cubic…