La despujolsite, une nouvelle espèce minérale

The new mineral, despujolsite, from Tachgagalt (Morocco) Ca₃Mn⁴⁺ [(SO₄)₂/(OH)₆] • 3H₂O is hexagonal P[˗6]2c, a = 8.56 ± 0.02, c = 10.76 ± 0.04 Å, Z = 2, dmes. = 2.46 ± 0.02. Uniaxial (+ ), nω = 1.656, nε = 1.682 ± 0.002. Color lemon-yellow. Chemical composition has been established both by electron micro-probe analysis and X-ray structure analysis. Manganese atoms which are along the 6₃ axis are surrounded by six (OH)⁻ ions and calcium atoms by four (OH)⁻ ions, four water molecules and two oxygen atoms belonging to the (SO₄)²⁻ tetraedra. Calcium and manganese polyhedra are comparable to those of jouravskite. Despujolsite is compared with the isomorphous mineral schaurteite Ca₃Ge⁴⁺ [(SO₄)₂/(OH)₆] • 3H₂O and the chemical formula discussed in relation to the density and optical properties. The name is proposed in honor of P. Despujols, the founder of the Service de la carte géologique du Maroc.