FELDSPAR 



219 



Principal production of feldspar in the rest of the 

 world in 1970 is in Europe, close to large markets 

 for glass and ceramics. Major producers are West 

 Germany, the Soviet Union, Italy, France and Nor- 

 way; smaller production came from Finland, Spain, 

 Yugoslavia, Poland, Sweden, and Portugal. In Africa, 

 the major producers are the Republic of South 

 Africa and Ethiopia ; in Asia, Japan, the Phihppines, 

 India, and Korea; in the Western Hemisphere, 

 Mexico, Argentina, and Colombia. 



The forecast demand for feldspar in the United 

 States in the year 2000, based on a projected growth 

 rate of gross national product, is 2-3 million tons 

 (Cooper and Wells, 1970, p. 983). Demand for feld- 

 spar will fluctuate mostly with demand for glass 

 containers, flat glass, and pottery. If a significant 

 amount of bottle glass is recycled or if the use of 

 throwaway bottles decreases, feldspar needs will 

 decrease. 



EXPLOITATION 



Feldspar was first mined in the United States in 

 1825. The mineral came from pegmatite bodies in 

 Connecticut and was shipped to England for use in 

 ceramics (DuBois, 1940, p. 207). Principal produc- 

 tion from 1853 to 1910 was from Connecticut, New 

 York, Maine, Pennsylvania, and Maryland. Although 

 there is a legend that the Indians mined and sold 

 semikaolinized feldspar from western North Caro- 

 lina before 1744, the first recorded shipment from 

 that State was made in 1911. Within several years 

 North Carolina became a major producer of feldspar 

 and has for many years accounted for at least half 

 of the annual U.S. production. In recent years Cali- 

 fornia, Connecticut, South Carolina, Georgia, and 

 South Dakota have been our other important feld- 

 spar producers. Production fluctuates from year to 

 year, but it has in general steadily increased since 

 1940, when use of feldspar in glass became common 

 (fig. 25). 



Most of the feldspar produced in the United States 

 until 1946 consisted primarily of perthite and oligo- 

 clase hand-cobbed from coarse-grained pegmatites. 

 In 1936, the U.S. Bureau of Mines began an investi- 

 gation of the concentration of feldspar by table 

 agglomeration and flotation (O'Meara and others, 

 1939). The first commercial plant to produce feldspar 

 for glass by flotation began operation at Kona, 

 Mitchell County, N.C., in 1946. Use of flotation per- 

 mitted low-cost mining of finer grained pegmatite 

 and granite and expanded the potential sources of 

 raw material. Quartz and flake mica are commonly 

 byproducts of flotation feldspar. Some flotation feld- 



spar is also produced as a coproduct in the mining 

 of lithium-rich pegmatites, especially in North Caro- 

 lina. Recent studies by the U.S. Bureau of Mines 

 and others have shown the practicability of produc- 

 ing feldspar, quartz, and mica concentrates from 

 granitic rocks (Hill and others, 1969) and of utiliz- 

 ing tailings from feldspar plants in North Carolina 

 (Redeker, 1970). 



In 1970, about 57 percent of the feldspar used in 

 the United States was taken from flotation concen- 

 trates, 8 percent was hand sorted, and 35 percent 

 was from feldspar-silica mixtures (Wells, 1972, p. 

 2). In 1955, these figures were 40, 45, and 15 per- 

 cent, respectively (fig. 25). 



Feldspar is mined by open-pit and underground 

 methods. Most of the mines producing ore for bene- 

 ficiation are open pits using power equipment and 

 yielding 300-800 tons per day. Selective mining is 

 done in zoned pegmatites, usually at a rate of less 

 than 100 tons a day. The broken rock is sorted by 

 hand during loading or on a picking belt. Feldspar 

 has also been produced as a byproduct of sheet-mica 

 mining, which requires the broken rock to be sorted 

 and moved by hand. The number of small producers 

 using hand-cobbing methods is decreasing as labor 

 and material costs increase ; in 1971, only four mills 

 in the United States were using hand-cobbed ore. 

 Details of the mining, beneficiation, and marketing 

 of feldspar are given by Castle and Gillson (1960), 

 Cooper and Wells (1970), and Feitler (1967). 



The average price of crude feldspar per long ton 

 was $14.87 in 1970 and $9.51 in 1960 (Wells, 1972, 

 p. 2). The average price of ground feldspar per 

 short ton was $14.60 in 1970 and $13.40 in 1960. 

 Prices quoted for ground feldspar for December 

 1970 were as follows: North Carolina 20 mesh, flo- 

 tation, $11.00; 200 mesh, flotation, $20.50-$26.00 

 (Engineering and Mining Journal, 1970) . 



Transportation cost is an important element in 

 marketing feldspar for glass because the delivered 

 cost per unit of alumina plus alkalies is the basis 

 for determining relative value of competing feldspar 

 products. Nepheline syenite from Canada has an 

 advantage over feldspar from Southern United 

 States in the glass markets of parts of New York, 

 New Jersey, Pennsylvania, and Ohio because of its 

 greater content of alumina plus alkalies and because 

 of more favorable freight rates. The ceramic indus- 

 try, however, is more concerned with a particular 

 feldspar and its effect on the delicate balance of 

 ceramic mix, plant operation, and product quality. 

 In general, one feldspar product cannot be substi- 

 tuted for another in a ceramic mix without extensive 

 tests. A ceramic feldspar is sometimes shipped past 



