Natural Gemstones
Quartz, Rhode Island.
Amethyst crystals, Mexico.
U.S. Department of the Interior U.S. Geological Survey
Searching for gemstones in the United States is a popular recreational activity for collectors and hobbyists
A natural gemstone is a mineral, stone, or organic matter that can be cut and polished or otherwise treated for use as jewelry or other ornament. A precious gemstone has beauty, durability, and rarity, whereas a semiprecious gemstone has only one or two of these qualities. A gem is a gemstone that has been cut and polished.
Diamond, corundum (ruby and sapphire), beryl (emerald and aquamarine), topaz, and opal are generally classed as precious stones. All other gemstones are usually classed as semiprecious.
A mineral is any naturally formed homogeneous inorganic material.
A mineralogist is a person who studies the formation, occurrence, properties, composition, and classification of minerals.
A gemologist is a person who has successfully completed recognized courses in gemology (the science and study of gemstones) and has proven skills in identifying and evaluating gem materials.
A lapidary is a cutter, polisher, or engraver of precious stones.
Gemstones are not plentiful. Gemstones do not form “ore” deposits in the normal sense.
Gems, when present at all, tend to be scattered sparsely throughout a large body of rock or to have crystallized as small aggregates or fill veins and small cavities.
Geological Survey
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Natural gemstones
Geologic environment
Gemstones occur in most major geologic environments.
Mineral gemstones
Birthstones
Organic gemstones
Buyer beware
Since 1935, the mining of gemstones in the United States has been almost entirely a recreational activity of mineral collectors and hobbyists.
The 1990 U.S. output of natural gemstones was primarily from Tennessee, California, Arizona, Arkansas, Montana, Nevada, and Maine.
Except for the few gem diamonds found each year in Arkansas, U.S. diamond production is very low.
World diamond reserves are estimated to be about 300 million carats, including near-gem materials but not diamonds of abrasive quality.
Chemical formulas of gemstones
Some ways to contact a local rock, mineral, or gem club
Role of the U.S. Geological Survey (USGS)
Selected general references
Acknowledgments
Photographs
Transcriber’s Notes