Minerals Yearbook, 1991: Feldspar, Nepheline Syenite, and Aplite

摘要

Domestic production data for feldspar are developed by the U.S. Bureau of Mines by means of a voluntary survey. Of the 12 active mill operations, 9 responded, representing 75% of the total canvassed. These nine respondents reported a production of 475,000 metric tons or about 82% of the total domestic production shown in table 1. The estimated production of nonrespondents, 105,000 tons, was derived from past years' production levels and trends.