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175 different compounds used by the chem- ical industry to make everything from cos- metics to toothpaste to carpets. Electricity, carried by aluminum power lines and copper wires to the glowing tungstenfilaments (from wolframite) of your incandescent lightbulbs, may have been generated using fossil fuels (coal or petroleum) or nuclear power, which depends on uranium ores such as uraninite, pitchblende, and carnotite. The fertilizers used to grow your fruits and vegetables may contain pulverized gypsum or limestone to reduce acidity, and apatite or sylvite to add phosphate. The insecticides and herbicides used to kill pests on these crops may have been made using coal extracts, arsenic, barium, sulfur, or fluoride. Quartz, mica, silver, copper and gallium may be critical components of your computer, television, watch or other electronic equipment. Look out your window. The window itself is made from soda ash, limestone, and melted quartz sand, which is high in silica content. The cars driving by may have shiny, non-rusting chrome trim, extracted from chromium ore (chromite); platinum, rhodium, or palladium to remove air pol- lution in their catalytic converters; tin, a tough, corrosion-resistant metal often used in bearings; and cobalt, zinc, or titanium in their paint. The road the cars are driving on is made out of asphalt (dolomite and other

Sphalerite is an ore of zinc, and is useful in making brass, galvanized steel, and batteries. Because sphalerite also contains sulfur, it smells like rotten eggs if hydrochloric acid is added to it. Sphalerite emits flashes of light when it is scratched in a dark room.

rocks mixed with the tar-like bitumen result- ing from coal or petroleum processing) and is probably laid down on a bed of gravel of crushed igneous rocks like basalt, gabbro, and diabase, which are noted for their toughness. The airplane passing overhead may contain titanium (from rutile), which is lightweight and highly resistant to high temperatures; an alloy of nickel and niobium (from colum- bite), which is strong and corrosion resistant and can withstand the high temperatures generated by a jet engine; and magnesium (from dolomite and magnesite), which is even lighter than aluminum. Other metallic min- erals added to change the properties of steel

Graphite, like diamond, is pure carbon; but diamond is the hardest mineral, while graphite is one of the softest. Graphite’s softness makes it useful in pencil lead, and its slippery feel makes it a good lubricant for machinery.

These limestone outcrops in Utah are being eroded by weather and by acids secreted by the lichens growing on their surface. As rocks are eroded they determine the characteristics of the soils around them. Limestone generally neutralizes soil acidity, thus affecting which plants can live there.

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