Butlerita (Fe OH SO4 2H2O) de la mina Santa Elena, provincia de San Juan, Argentina

Resumen

Butlerite (Fe OH SO₄ 2H₂O) from Santa Elena mine, province of San Juan, Argentina. Idiomorphic crystals of Butlerite from Santa Elena mine, Calingasta, San Juan, Argentina, were used for this study. Butlerite (Fe OH SO₄ 2H₂O) has the following characteristics: monoclinic, Prismatic class, space group P 2₁/m; a = 6.499(1), b = 7.378(1), c = 5.848(1)Å, ß = 108º28'(5), a:b:c = 0.8809:1:0.7926, cell volume 265.98 ų, Z=2. The transparent crystals are colorless to pale yellow, the fine aggregates are yellow orange, the streak is pale yellow, the luster is vitreous. The crystals are tabular, measuring up to 1 mm across; the predominant forms are {001}, {100}, {110}, {011}, and {101}. The strongest peaks in the X-ray powder diagram are, in Å: 4.98 (100), 3.165 (52), 3.597 (17), 3.234 (14), 2.495 (14), 4.74 (9), 4.43 (9). Butlerite is biaxial (+), a = 1.595(1), ß = 1.666(1), g = 1.743(1) Na light, 2 V 85º, Z = b, XÙ c = -17º, pleochroism X = colorless, Y = faint yellow, Z = light yelow, high birefringence, cleavage {100} very good, fragile, hardness 2 1/2, density 2.552 g/cm³ (meas.), 2.559 g/cm³ (calc.). Parabutlerite, the orthorhombic dimorph, dipyramidal class (2/m 2/m 2/m), spatial group Pmnb, is associated with butlerite.