250 



UNITED STATES MINERAL RESOURCES 



as the abundant pegmatites of Brazil and the Mala- 

 gasy Republic, or the extensive placer deposits of 

 southern Asia, are not known in the United States. 

 The few American deposits which produced ruby, 

 sapphire, emerald, beryl, and tourmalines commer- 

 cially ceased doing so years ago. Since about 1935 

 the production of gem stones in the United States 

 has been restricted very largely to turquoise, jadeite, 

 nephrite, opal, aventurine, and the cryptocrystalline 

 silica minerals agate, petrified wood, chalcedony, 

 chrysoprase, and jasper. In total value the silica min- 

 erals overwhelm all the others. Nearly all the gem 

 stone production of the last 40 years has come from 

 Texas and the States west of the Great Plains, but it 

 is impractical to enumerate here all of the gem stone 

 localities of even the Western States. 



UNITED STATES PRODUCTION 



The mining of gem stones in the United States 

 since about 1935 has been almost entirely a recrea- 

 tional activity of mineral collectors and hobbyists. 

 Estimates of the number of individuals in recent 

 years whose entire income is derived from gem 

 stones mined by themselves have ranged from only 

 8 to about 30. 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 rich in gem 

 materials, and the operators tend to specialize in the 

 local gem commodities, most of which they gather 

 themselves. Owners of properties containing gem 

 materials, rather than doing the mining themselves, 

 sometimes charge hobbyists for the privilege of col- 

 lecting gem stones. Diamond in Arkansas, opal in 

 Idaho, and agate in Oregon and Washington are 

 mined by hobbyist under this type of "fee digging" 

 arrangement, it is not usually, however, the value 

 of the stones produced and sold in an area or the 

 generally small fees collected by property owners 

 that are the most significant contributions to the 

 local economy of areas productive of gem stones ; 

 rather, it is the cost-of-living expenses of the hobby- 

 ists while afield. Moreover, with the growing popu- 

 larity of lapidary work and of "rock hounding" 

 among all age groups in the United States, and with 

 the steadily increasing number of older people, many 

 of whom are retired and have time available to pur- 

 sue the hobby, both gem production and the economy 

 of gem-producing areas are likely to increase sub- 

 stantially in the future. It is not paradoxical, there- 

 fore, that the United States, which has no major 

 gem stone deposits and no organized gem-producing 

 industry, still has been able to increase the value of 

 its gem production from half a million dollars in 

 1952 to nearly $3 million in 1972 ; the annual value of 



gem stones produced 20 years hence probably will be 

 several times $3 million. 



IMPORTS AND EXPORTS 



The United States is a large importer of gems, 

 mostly the "precious" stones diamond and emerald, 

 of which the United States has only minuscule do- 

 mestic production. Diamond once made up nearly 95 

 percent of all gem imports ; and although it has now 

 dropped to about 80 percent, current import of cut 

 diamond is about $200 million annually, and import 

 of uncut diamond is about $300 million. Cut emerald 

 is imported at a rate of about $10 million annually, 

 and in some recent years the import of synthetic 

 stones has been nearly this much. Pearls and other 

 gem materials, including imitation stones, constitute 

 only a few percent of the value of all gems imported. 



The value of gem stones exported from the United 

 States is about $200 million per year. The reexport 

 of diamond, cut in this country from imported un- 

 cut stones, accounts for much of this, but an increas- 

 ing percentage is made up of synthetic stones. There 

 is also a small but steadily increasing export of 

 natural domestic gem materials to Germany, Tai- 

 wan, and elsewhere for fabrication. Principal among 

 these materials are turquoise and the jade minerals, 

 as well as quantities of massive actinolite, pink dolo- 

 mite, banded rhyolite, and other ornamental stones. 



SELECTED REFERENCES 



Ball, S., H., 1922, The geolo^c and geographic occurrence of 

 precious stones : Econ. Geology, v. 17, no. 7, p. 575-601. 



1931, Historical notes on gem mining: Econ. Geology, 



V. 26, no. 7, p. 691-738. 



1935, A historical study of precious stone valuation 



and prices: Econ. Geology, v. 30, no. 6, p. 630-642. 



1949, Precious stones, in Industrial minerals and 



rocks [2d ed.] : Am. Inst. Mining and Metall. Engi- 

 neers, New York, p. 714-747. 



Bauer, M. H., 1896, Edelsteinkunde (English translation, 

 1904, by L. J. Spencer) : Reprinted 1968 by Dover Pub- 

 lications, New York, 627 p. (2 vol.). 



Comstock, H. B., 1970, Gem stones, in Mineral facts and 

 problems: U.S. Bur. Mines Bull. 650, p. 1013-1023. 



Fleischer, Michael, 1971, Glossary of mineral species, 1971 : 

 Mineralogical Record, Bowie, Maryland, 103 p., ap- 

 pendix. 



French, A. E., 1968, Gem-stone, mineral, and fossil collect- 

 ing, in Mineral resources of the Appalachian region: 

 U.S. Geol. Survey Prof. Paper 580, p. 288-302. 



Jahns, R. H., 1960, Gem stones and allied materials, in In- 

 dustrial minerals and rocks [3d ed.] : Am. Inst. Mining 

 Metall., and Petroleum Engineers, New York, p. 383- 

 441. 



Petkof, Benjamin, 1965, Gem stones, in Mineral facts and 

 problems: U.S. Bur. Mines Bull. 630, p. 361-377. 



Schlegel, D. M., 1957, Gem stones of the United States: 

 U.S. Geol. Survey Bull. 1042-G, p. 203-253. 



