However, the flow of money into the local economy by paying these small fees and by the purchase of gemstones is minor compared to the money the enthusiasts spend for lodging and other living expenses while visiting an area to dig for gemstones. Several kinds of natural gemstones have been found in every State of the United States, but much larger deposits of the most precious kinds are found outside the United States. The 1990 U.S. output of natural gemstones was primarily from Tennessee, California, Arizona, Arkansas, Montana, Nevada, and Maine. An estimated 80,000 visitors found a total of 315 carats of diamonds in the Crater of Diamonds State Park in Arkansas. There were sizeable yields of freshwater pearls in Tennessee, turquoise in Arizona and Nevada, tourmaline in Maine, and tourmaline, kunzite, and garnet in California. Gemstones: Value of U.S. production vs. imports, 1986 and 1989[1] Production 1986 1989 Natural $9.3 million $43.0 million[2] Synthetic 10.3 23.5 $19.6 $66.5 Mine employment 300 800 Imports for consumption: $4.18 billion $5.00 billion Apparent reliance on imports over 99% 98% exports[3] [1]Estimated. [2]Including freshwater pearls natural, and cultured. [3]Imports - exports + adjustments for Government and industry stock changes. Source: _Mineral Commodity Summaries_, 1991, U.S. Bureau of Mines. U.S. production of commercial gems includes agate, beryl, freshwater pearl, garnet, jade, jasper, mother-of-pearl, opal, peridot, quartz, sapphire, tourmaline, and turquoise. Except for the few gem diamonds found each year in Arkansas, U.S. diamond production is very low. Yet exploration for diamonds continues in Alaska, Colorado, Michigan, Minnesota, Wisconsin, and Wyoming. A diamond mining project at the Crater of Diamonds State Park in Arkansas is still being evaluated by the State. World diamond reserves are estimated to be about 300 million carats, including near-gem materials but not diamonds of abrasive quality. Most of the reserves are in southern Africa, Siberia, and western Australia. It is difficult to estimate reserves because the value of a given deposit varies with the market for the gems. [Illustration: Jade nephrite, China.] [Illustration: The Hope Diamond, India.] Chemical formulas of gemstones