Abstract

Braitschite, a new hydrous calcium rare-earth borate mineral occurs in the Cane Creek potash mine of the Texas Gulf Sulphur Company and in a core hole one mile south of the mine, near Moab, Grand County, Utah. The braitschite is in white to reddish-pink nodules which constitute a zone in anhydrite rock immediately overlying a potash bed, throughout the workings of the mine. The nodules contain approximately 65 percent braitschite and about 35 percent quartz, anhydrite, dolomite, halite, small amounts of hematite, and a few crystals of chalcopyrite. Crystals of braitschite are colorless to white, very small hexagonal plates with only pinacoid and prism forms. Specific gravity is 2.903 ± 0.002 (meas.), 2.837 (calc.). Optically uniaxial positive, ϵ =1647, ω = 1.646. The analyzed sample contained minor amounts of quartz, dolomite, hematite, and a chlorite-like mineral. The analysis of braitschite, recalculated for these impurities, is CaO 21.8, Na2O 1.68, Y2O3 1.50, La2O3 4.57, Ce2O3 7.64, Pr2O3 1.00, Nd2O3 3.67, Sm2O3 0.941, Eu2O3 0.390, Gd2O3 0.320, Tb2O3 0.103, Dy2O3 0.250, Ho2O3 0.054, Er2O3 0.081, Tm2O3 0.023, Yb2O3 0.018, Lu2O3 0.010, B2O3 48.2, H2O 7.75, sum 100.00%. The unit cell is hexagonal, a = 12.156 ± 0.001 Å, c = 7.377 ± 0.005 Å, V=944.02 + 0.13 Å3, Z= 1. Strongest lines of the X-ray diffraction pattern (in Å) are: 10.52 (54) (100); 4.283 (100) (201); 3.168 (45) (301); 3.155 (38) (112); 3.021 (92) (202); 2.8090 (53) (221); 2.1430 (30) (402); 1.9117 (34) (233); 1.8805 (35) (313).

Braitschite is named in memory of the late Professor Dr. Otto Braitsch, Univerity of Freiburg, Germany.

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