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National Geographic : 1974 Feb
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relate only to rock collecting, and leaves minerals and mineralogy somehow unac counted for. While most collectors are like ly to own both rocks and minerals, there are many who devote themselves exclusively to specimens of mineral crystals-the amateur mineralogists. Minerals Basic to Life What are rocks and minerals, anyway? And why are they important? Says Dr. Joel E. Arem, Harvard-trained mineralogist, lecturer, and gemologist: "There are basically two components of this world, minerals and energy. Even water is a mineral. Minerals are made up of ele ments, and from them everything else pro ceeds. Plants, animals, man. A plant requires minerals and energy to grow. So there is noth ing more basic to our existence than minerals." There are about 2,200 of them, with more being scientifically identified every year. They have their own chemical and atomic compositions, each crystallizing in forms de termined by the internal arrangements of its atoms. Salt and fluorite grow as cubes; beryl, apatite, and tourmaline take the shape of hex agonal pencils. There are six basic geometric crystal types, and dozens of variations and combinations (pages 288-9). All rocks are composed of minerals. Oc casionally a rock may be one single mineral. Sandstone may be pure quartz; soapstone, pure talc; marble, pure calcite. However, most rocks (there are hundreds of kinds) are made up of two or more minerals. What are called gemstones include not only single minerals like malachite, and mineral crystals like emerald and diamond, but rocks of great beauty as well. Lapidary artists fashion these gemstones into an infinite variety of decorative objects. Traveling across the continent, I met the rock collectors on their mountains and sea shores, the mineral collectors in their mines and caves and quarries, the lapidaries in their basement workshops and garages, and the serious students in their home libraries and at their scientific lectures. They proved to be a disparate group in other ways as well. The youngest I met was Carrie Jane Woodward of Prineville, Oregon, age 4. Her sharp eyes could spot the slightest chip of agate broken off into the dirt by the prospector's pickax in the hands of Craig Woodward, her father. 282 WILLIAM M. LAMPdtLL
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