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.

Gemstones: Value of U.S. production vs. imports, 1986 and 1989[1]

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