Table 2.--Domestic mine production
                                                              (Metric tons)
                                          -----------------------------------------------------
                                                                             Dry
                                          Year                 Crude     equivalent     Value1/
                                          -----------------------------------------------------
                                          1970---------        2,562        2,115        30,070
                                          1971---------        2,458        2,020        28,543
                                          1972---------        2,235        1,841        23,238
                                          1973---------        2,324        1,909        26,635
                                          1974---------        2,408        1,980        25,663
                                          1975---------        2,199        1,801        25,083
                                          1976---------        2,420        1,989        26,645
                                          1977---------        2,436        2,013        27,555
                                          1978---------        2,066        1,669        23,185
                                          1979---------        2,186        1,821        24,875
                                          1980---------        1,869        1,559        22,353
                                          1981---------        1,847        1,510        26,489
                                          1982---------          896          732        12,334
                                          1983---------          826          679        11,309
                                          1984---------        1,054          856        15,643
                                          1985---------          787          674        12,855
                                          1986---------          617          510        10,361
                                          1987---------          689          576        10,916
                                          1988---------          714          588        10,566
                                          1989---------            W            W             W
                                          1990---------            W            W             W
                                          -----------------------------------------------------
                                            W  Withheld to avoid disclosing company proprietary
                                          data.
                                            1/Computed from values assigned by producers and
                                          from estimates of the U.S. Bureau of Mines.

                                            Source: U.S. Bureau of Mines Minerals Yearbook.