National Geographic : 1951 Nov
"Rockhounds" Uncover Earth's Mineral Beauty BY GEORGE S. SWITZER Associate Curator of Mineralogy, U. S. National Museum YEARS ago when I first became a "rock hound," a friend and I were collecting minerals in Death Valley, California. At nightfall we built a fireplace with sev eral large rocks, started a fire, and set some beans to heating. Then suddenly our fireplace began to ex plode! We had not realized that the rocks contained colemanite, a mineral which vio lently flies apart into a powder when heated. Our dinner that night consisted of a hard-to digest mixture of colemanite and beans. Thus, in a rather explosive fashion, we added one more item to our knowledge of minerals. Hobby Dates from Earliest Times The world's first mineral collector prob ably was some savage whose eye was attracted by the beauty of a colored pebble or shining piece of rock crystal. From earliest times men have collected attractive stones, minerals, and unusual fos sils and often have looked with superstitious awe upon specimens whose origin they could not explain. Fossilized shark's teeth long were thought to be objects which fell to earth during eclipses of the moon. Some ancient peoples even believed that certain stones brought forth young! * Today's rock hunters, free of superstition and armed with true understanding of Na ture's processes, are finding beauty hidden in the drab earth, unsuspected not only by their primitive forebears but by most people even in modern times. Rockhounds don't just collect rocks. De spite the name of their hobby, their real inter est lies in the minerals of which rocks are composed. Born of the mighty forces of Na ture, sometimes deep in the earth, sometimes at or near its surface, eons ago or even in recent times, these minerals give a broad range of beauty and interest to what the aver age person thinks of as merely rocks. A rock is really an aggregate of minerals. Ordinary granite, for example, is a hard, com pact aggregate of feldspar, quartz, amphibole, and biotite. Other rocks may be essentially one mineral; sandstone, for example, is mostly quartz, limestone is mostly calcite (page 634). Fossilized bones, shells, and wood also are collected by many rockhounds. Sometimes the original bone, shell, or wood gradually has been carried away bit by bit by under ground water over vast stretches of time and replaced, cell by cell, with some mineral dis solved in this same water. Such fossils are unchanged in form, but have been completely transformed into opal, quartz, pyrite, or other minerals (pages 642, 651). Hundreds of Thousands of Devotees In the last 15 years the number of mineral collectors has grown enormously. Today, in the United States alone, they number at least 200,000; some estimates run well over a mil lion. Here is a hobby that has everything. It offers healthful outdoor exercise, adventure, an introduction to a new world of beauty and color, a knowledge of geography and geology, and a chance to make important contributions to the science of mineralogy. One may enjoy minerals as jewels of rare beauty, for diamond, ruby, sapphire, and other precious gems are minerals.t Then, too, fine natural crystals of some minerals even surpass in beauty gems whose surface has been modi fied by cutting and polishing. Like stamp collectors, rockhounds learn geography through their collections. Every country in the world offers minerals of special interest, beauty, or rarity. America's great "master collection" of min erals in the U. S. National Museum, Wash ington, D. C., administered by the Smith sonian Institution, was gathered almost en tirely by two amateurs who devoted many years and large fortunes to their hobby (pages 640, 641). Most other important mineral collections also were gathered largely by amateurs. No branch of science owes more to the work of amateur hobbyists than does that of miner alogy. Starting Is Easy, Equipment Simple Since there are only about 1,600 well-defined species of minerals, a diligent collector can learn to know all the common ones and many that are rare. Discovery of a new mineral is truly a feat of which to be proud. Finding a new species is an event of far greater im portance, for example, than the discovery of a new insect, for the known species of insects described to date already number around three-quarters of a million. * See "Earth's Most Primitive People," by Charles P. Mountford; NATIONAL GEOGRAPHIC MAGAZINE, January, 1946. t See "Exploring the World of Gems," by W. F. Foshag, NATIONAL GEOGRAPHIC, December, 1950.