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Garnet, January’s Birthstone by Harry W. Short Engineering Geologist If Great Aunt Millie's birthday falls in January, consider buying her jewelry with a garnet gemstone. Garnets sym- bolize grace, truth, and fidelity. The an- cients were fascinated by its bright, deep red color. It comes in several other colors, except blue. Different varieties of garnet occur in shades of red and violet, pale green, orange-yellow to orange brown, deep green to transparent green, and yel- low-green to black. Garnets are iron rich with oxides of aluminum and silica, the common ingredient of which quartz is composed. The various colors in garnets are derived from calcium, magnesium, manganese, and chromium ions which substitute (replace) iron in the mineral. Substitution occurs when several ions of calcite and chromium gang up on the iron and aluminum ions. This causes the color to change and impacts the stone's physical properties to the crystal structure, making garnets valuable as gemstones and used in industrial applications. Garnets are composed of common elements found abundantly in the earth's crust, such as aluminum, silica, oxygen, iron, calcium, and manganese. Crystalline garnets are found in metamorphic rocks, schist, gneiss, and as secondary or accessory minerals in igneous rocks. Pyrope, the manganese variety of garnet, occurs in dark-colored igneous rocks called peridotites and kimberlites. Since garnets are hard, they’re often found in streams as placer deposits and can be mined with draglines or dredges. The hardness of garnets makes the nongemstone iron-rich variety, almandine, valuable as an abrasive used to manufacture sandpaper and grinding wheels. They can be used for sandblasting, water jet cutting, and ground into a fine media for tumble polishing other rock or mineral materials in the lapidary arts. Garnets are also used to prepare nonskid surfaces, and as a filter media for various fluids. In 1999, the United States mined over 25% of the 214,000 tons of the world’s supply of garnets. The majority of U.S. garnets come from the Adirondack Mountain region in New York State. Other garnet-producing states include Idaho, Maine, Montana, New Hampshire, North Carolina, and Oregon. The three major worldwide producers of garnets are Australia, India, and China, with lesser amounts from Russia, Turkey, Norway, Canada, the Czech Republ ic, Pakistan, and the Ukraine. Don't forget to remindAunt Millie each January that the pretty red stone on the necklace you bought to commemorate her birthday is not an ordinary gemstone, it's a garnet! Harry Harry Short may be contacted via e-mail to michele@ worldwidedrillingresource.com 8 $04(-& 2'$ #0(++(-& (-#31207 1(-"$ 9 8 '$- (2 ".,$1 2. : ; 5$ *-.5 2'$ 9 $12 0!-*%.02 ++(-.(1 ."!2(.- ,!(+ 2$$)!7 ,(#5$12 -$2 !6 .++ 0$$ 0$2(/ %.0 23 WorldWide Drilling Resource ® JANUARY 2016 On January 18, 1930, oil producers met in Wichita Falls to organize today’s Texas Alliance of Energy Producers.