Part 4

More and more synthetic gems—and inferior grades and cuts of natural gems—are being sold to unwary buyers by unscrupulous sellers.

Since 1935, the mining of gemstones in the United States has been almost entirely a recreational activity of mineral collectors and hobbyists.

In recent years, very few individuals have derived their entire income from gemstones mined by themselves.

This is not to say that the proprietors of roadside rock shops buy all of their stock from others. Rock shops are abundant in areas of the United States that are rich in gem materials, and the shops tend to specialize in the local gem commodities, most of which the proprietors gather.

Rather than doing the mining themselves, owners of land that has a deposit of gem-quality minerals sometimes charge hobbyists for the right to collect gemstones. For example, diamond in Arkansas, opal in Idaho, and agate in Oregon and Washington are mined by hobbyists under this “fee digging” arrangement.

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

Production 1986 1989 Natural $9.3 million $43.0 million 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

Estimated.

Including freshwater pearls natural, and cultured.

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.

Chemical formulas of gemstones

Beryl BeࠣAlࠢSiࠦO₁ࠨ Chrysoberyl BeAlࠢOࠤ Coral CaCOࠣ Corundum AlࠢOࠣ Diamond C Feldspar Plagioclase Series: (Na,Ca)Al(Al,Si)SiࠢOࠨ Alkali Feldspar Group: Mixtures of Orthoclase—KAlSiࠣOࠨ and Albite—NaAlSiࠣOࠨ Garnet Almadine—FeࠣAlࠢ(SiOࠤ)ࠣ Andradite—CaࠣFeࠢ(SiOࠤ)ࠣ Grossular—CaࠣAlࠢ(SiOࠤ)ࠣ Pyrope—MgࠣAlࠢ(SiOࠤ)ࠣ Spessartine—MnࠣAlࠢ(SiOࠤ)ࠣ Uvarovite—CaࠣCrࠢ(SiOࠤ)ࠣ Jade Nephrite—Caࠢ(Mg,Fe)ࠥ(SiࠨOࠢࠢ) (OH)ࠢ Jadeite—NaAl(SiࠢOࠦ) Lapis lazuli Lazurite—(Na,Ca)ࠨ(AlSiOࠤ)ࠦ (SOࠤ,S,Cl)ࠢ Opal Hydrated Silica—SiOࠢ·nHࠢO Peridot (Mg,Fe)ࠢ(SiOࠤ) Quartz SiOࠢ Spinel MgAlࠢOࠤ Topaz AlࠢSiOࠤ(F,OH)ࠢ Tourmaline XYࠣAlࠦ(BOࠣ)ࠣ(SiࠦO₁ࠨ) (OHࠤ) [X is usually Na but may be replaced by Ca; Y is one of several metal ions] Turquoise CuAlࠦ(POࠤ)ࠤ(OH)ࠨ·4HࠢO Zircon ZrSiOࠤ

Some ways to contact a local rock, mineral, or gem club

If you have access to the most recent April Buyer’s Guide issue of the Lapidary Journal magazine, scan its lists of gem and mineral clubs in the United States and other countries. (The address of the Lapidary Journal is given in the list of journals cited below.)

Talk to a member of the geology or earth science department of your local college or university.

Talk to a member of the science department of your local high school.

Write to the—

Eastern Federation of Mineralogical and Lapidary Societies Box 10119 Alexandria, VA 22310-0119

or the