美国矿业局初步估计,1987年美国球土产量比1986年增长了4.5%,达到84.3万吨,价值3600万美元。田纳西州球土产量占球土总产量的70%。艺术瓷、餐具瓷、卫生瓷、耐火材料和瓷砖等大多数工业部门,增加了对球土的需求量。这反映出在消耗进口的条件下,国内经济的兴旺和生产的发展。球土工业仍有发展潜力,因为其产品的单位产值变化不大。1987年美国膨润土产量比1986年降低了 The U.S. Bureau of Mines initially estimated that the U.S. geotechnical output in 1987 grew by 4.5% from 1986 to reach 843,000 tons, worth US$36 million. Tennessee ball soil production accounts for 70% of the total ball soil output. Most of the industrial sectors such as art porcelain, tableware porcelain, sanitary porcelain, refractories, and ceramic tiles have increased the demand for ball clay. This reflects the prosperity of the domestic economy and the development of production under the conditions of consumption of imports. The ball and soil industry still has potential for development because the unit output value of its products does not change much. Bentonite production in the United States decreased by 1987 compared with 1986