class="l">XY₃Al₆(BO₃)₃(Si₆O₁₈) (OH₄)

[X is usually Na but may be replaced by Ca; Y is one of several metal ions] Turquoise CuAl₆(PO₄)₄(OH)₈·4H₂O Zircon ZrSiO₄

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—

or the

Check the phone book for your nearest rock and mineral shop and talk to the owners.

Role of the U.S. Geological Survey (USGS)

The USGS reports deposits that seem likely to contain gemstones. It is not a function of the USGS to exploit such resources.

USGS geologists perform continuing research on kimberlites, the initial source of diamonds. Not all kimberlites are diamond-bearing, and some of the research is directed to learning what indications you look for during exploration to distinguish fertile from barren kimberlite. USGS geologists are compiling a U.S. map showing the locations of known kimberlites.

Selected general references

A trip to your local library is the best first step toward understanding gemstones and toward planning a trip to gem and rock shops or to places where you may be able to collect gemstones.

A list of Selected references on rocks, minerals, and gemstones is compiled and updated every two years by the USGS Geologic Inquiries Group, 907 National Center, Reston, VA 22092; (703) 648-4383. The list has three sections: selected guides for rockhounds and hobbyists, general references for all ages, elementary school to adult, and periodicals.

The guides in Section I tell about equipment needed for collecting, etiquette of collecting, map reading, organizing a collection, collecting localities by States, mineral societies, mineral show dates and locations, and rock, mineral, and fossil dealers.

The references below focus mainly on natural gemstones and the gems made from them rather than on synthetic gemstones, rocks, or other nongem minerals.

Minerals Yearbook

The relatively few pages on gemstones in the multivolume Minerals Yearbook provide data on sources, kinds, and volume of domestic production, domestic consumption, prices, and foreign trade. This U.S. Bureau of Mines yearbook is in the reference sections of many major libraries. It can be purchased from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.

Books

Gemology, Cornelius S. Hurlbut Jr. and Robert C. Kammerling: John Wiley & Sons, New York, 1991, 2nd ed.

Gemstones and Their Origins, Peter C. Keller: Van Nostrand Reinhold, 1990.

Color Encyclopedia of Gemstones, Joel Arem: Van Nostrand Reinhold, New York, 1987, 2nd ed., 68 p.

Gemstones for Everyman, B.W. Anderson: Van Nostrand Reinhold, 1976, 268