La despujolsite, une nouvelle espèce minérale

Abstract

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.

Redetermination of despujolsite, Ca3Mn4+(SO4)2(OH)6·3H2O

“…For the previous determination of the despujolsite crystal structure, see: Gaudefroy et al (1968). For background to fleischerite, see: Otto (1975).…”

“…1.4806 18Symmetry codes: (i) Àx þ y þ 1; Àx þ 1; z; (ii) x; y; Àz þ 1 2 ; (iii) x À 1; y; Àz þ 1 2 ; (iv) Àx þ y; Àx þ 1; z. Data collection: APEX2 (Bruker, 2003); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: Xtal-Draw (Downs & Hall-Wallace, 2003); software used to prepare material for publication: SHELXTL (Sheldrick, 2008b (Gaudefroy et al, 1968;Otto, 1975), both of which were based on X-ray diffraction intensity data measured from photographs, without H atom positions located. An R-factor of 0.162 was obtained for the structure model of despujolsite (Gaudefroy et al, 1968).…”

“…Data collection: APEX2 (Bruker, 2003); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: Xtal-Draw (Downs & Hall-Wallace, 2003); software used to prepare material for publication: SHELXTL (Sheldrick, 2008b (Gaudefroy et al, 1968;Otto, 1975), both of which were based on X-ray diffraction intensity data measured from photographs, without H atom positions located. An R-factor of 0.162 was obtained for the structure model of despujolsite (Gaudefroy et al, 1968). In our efforts to understand hydrogen bonding environments in general and the relationships in the hydrogen bonding schemes in the minerals of the fleischerite group in particular, we noted that the structural information of despujolsite needed to be improved.…”

“…The crystal structure of despujolsite [tricalcium manganese bis(sulfate) hexahydroxide trihydrate], the Ca/Mn member of the fleischerite group, ideally Ca 3 Mn 4+ (SO 4 ) 2 (OH) 6 Á3H 2 O, was previously determined based on X-ray diffraction intensity data from photographs, without H-atom positions located [Gaudefroy et al (1968). Bull.…”

A new copper sulfate-carbonate hydroxide hydrate mineral, (Mn,Ni,Cu)8(SO4)4(CO3)(OH)6 48H2O, from Nakauri, Aichi Prefecture, Japan.

“…Only two sulfate-carbonate hydroxide hydrate minerals have been reported so far: carbonate-cyanotrichite (Ankinovich et al, 1963) and jouravskite (Graudefroy and Permingeat, 1965). Nakauriite is the third (Manuscript recieved, April, 2, 1976) one of this kind.…”