Cookeite from antimony veins of the Caracota mine, Bolivia

抄録

Cookeite was found in stibnite-pyrite-quartz veins of the Caracota mine, Bolivia. It is commonly ivory white in color with a pearly luster. The wet chemical analysis (containing 2.70 wt% Li₂O) gives the formula of Li_0.975(Al_3.921Na_0.060Ca_0.039Mg_0.017Fe_0.006³⁺)_4.043 (Si_3.064Al_0.936)_4.00O₁₀(OH)₈. The X-ray powder diffraction gives a pattern of Ia cookeite and the cell dimensions of a = 5.163(2), b = 8.957(2), c = 14.235(2)Å and β = 97.07(3)°. The results examined from optical properties, specific gravity, and an infrared spectrum warrant the substantial cookeite.