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THE SIGNIFICANCE OF ROCKS AND MINERALS Practically everything we do or use in our daily lives depends on materials extracted from the ground. The history of man’s exploration of the world and our waging of war has often centered around obtaining access to strategic mineral resources that are usually the basis for the wealth of a nation. The lust for gold funded much of the exploration and conquest of the Americas by Europeans. Some mod- ern-day conflicts, such as the Persian Gulf War and conflicts between indigenous people and oil companies in the Amazon Basin, are rooted in our dependence on oil or other min- eral resources. Uses of Rocks and Minerals Look around you now and see all the things that are made out of rocks and minerals mined from the ground. The paper of this book, though mostly plant fiber, has proba- bly been synthesized using kaolin, sulfur, and barium (from barite). The film used to photo- graph the illustrations uses silver mined from the ores argentite and chlorargyrite. Metals, extracted from ores such as hematite (iron),

Quartz occurs in many forms and colors, but clear crystals like this are rare. Clear quartz is used in making lenses and is an important component of watches, television, and radar apparatus. Striking two pieces of quartz together will produce a spark and a match-like odor.

sphalerite (zinc), bauxite (aluminum), cuprite (copper), galena (lead), nickeline (nickel), and cassiterite (tin), have given us all kinds of metal objects including cans, cars, coins, building mate- rials, and alloys such as pewter, bronze, brass, and stainless steel. The ubiquitous material plas- tic, which we use more of than steel, aluminum, and copper combined, is synthesized from petro- leum, the mineral remains of ancient plankton. Petroleum is also used tomake the rayon, Dacron polyester, or nylon you may be wearing, the gas- oline that powers your automobile, and over

Following page: Where rocks grind past each other along fault lines, they fragment into angular chunks of rock of varying sizes. These may then be surrounded by a mineral matrix and resolidify like this breccia specimen from Texas.

Some minerals occur in flowerlike formations like these barite roses. Barium, extracted from barite, shows up well in X-rays and

Pebble beaches are excellent places to search for stones that have been beautifully rounded and polished by the churning surf. This beach has quartz, porphyry, basalt, and gneiss mixed with an abundance of granite.

is used medically to help diagnose disorders of the

digestive tract. This Rumanian specimen also contains realgar, an ore of the toxic element arsenic.

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