ISSN:
1438-1168
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Description / Table of Contents:
Summary Three new selenides occur in the uranium mineralization rich in selenides and sulphides at Chaméane, France. Geffroyite, (Cu, Fe, Ag)9(Se, S)8, cubic,Fm3m,a=10.889 Å,Z=4; pentlandite-like structure. Calculated density 5.39 g/cm3. The strongest lines in the X-ray powder pattern are: 9 3.282 (311); 9 3.145 (222); 6 2.094 (511; 333); 10 1.925 (440); 5 1.660 (533); 6 1.112 (844). Vickers microhardness 70 kg/mm2. In reflected light, it has a brown colour with a cream tint. Reflectances: 19.0 (420), 27.5 (500), 30.1 (540), 33.6 (600), 35.8 (660), 36.9 (700 nm). Chaméanite. Microprobe analyses gave (Cu3.46Fe0.52)3.98(As0.94Sb0.02)0.96(Se3.72S0.34)4.06; ideal formula is (Cu, Fe)4As(Se, S)4. The Cu/Fe ratio varies from 6 to 13. CubicI---,a=11.039 Å,Z=8, calculated density 6.17 g/cm3. Strongest lines in the powder pattern: 10 3.187 (222); 9 1.951 (440); 8 1.665 (622); 4 1.381 (800); 6 1.266 (622); 7 1.127 (844); 5 1.062 (10.2.2; 666). Vickers microhardness 265 kg/mm2. Dark grey in reflected light. Some grains exhibit irregular zoning due to variations of Cu/Fe ratio. Maximum reflectances: 27.1 (420), 26.6 (500), 27.1 (540); 27.7 (600), 28.2 (660), 28.7 (700 nm). Giraudite, (Cu, Zn, Ag)12(As, Sb)4(Se, S)13. Cubic, $$I\bar 43m$$ ,a=10.578 Å,Z=2; member of tetrahedrite series. Arsenian analogue of hakite. Calculated density 5.75 g/cm3. Strongest lines in the powder pattern: 10 3.050 (222); 5 2.497 (411; 330); 6 1.932 (521); 9 1.868 (440); 7 1.593 (622). Vickers microhardness 293 kg/mm2. Light grey in reflected light, reflectances: 32.2 (420), 31.6 (500), 31.7 (540), 31.7 (600), 31.5 (660), 30.8 (700 nm). The mineralization of the Chaméane deposit consists of three cycles separated by tectonic movements. The minerals found are: barite, pitchblende, hematite, löllingite, arsenopyrite, pyrite, chalcopyrite, clausthalite, tetrahedrite, tennanite, bukovite, athabascaite, umangite, berzelianite, klockmannite, eucairite, geffroyite, chaméanite, giraudite and eskebornite.
Notes:
Résumé Trois séléniures nouveaux ont été découverts dans la minéralisation unranifère à séléniures et sulfures de Chaméane, France. Geffroyite, (Cu, Fe, Ag)9(Se, S)8, cubique,Fm3m,a=10.889 Å,Z=4; structure type pentlandite. Densité calculée 5.39 g/cm3. Les raies les plus intenses du diagramme de poudre sont: 9 3.282 (311); 9 3.145 (222); 6 2.094 (511;333); 10 1.925 (440); 5 1.660 (533); 6 1.112 (844). Microdureté Vickers 70 kg/mm2. Brun crème en lumière réfléchie, réflectances: 19.0 (420), 27.5 (500), 30.1 (540), 33.6 (600), 35.8 (660), 36.9 (700 nm). Chaméanite. Les analyses à la microsonde correspondent à (Cu3.46Fe0.52)3.98 (As0.94 Sb0.02)0.96(Se3.72S0.34)4.06, formule idéale (Cu, Fe)4As(Se, S)4. Le rapport Cu/Fe varie de 6 à 13. Cubique,I---,a=11.039 Å,Z=8, densité calculée 6.17 g/cm3. Raies les plus intenses du diagramme de poudre: 10 3.187 (222); 9 1.951 (440); 8 1.665 (622); 4 1.381 (800); 6 1.266 (662); 7 1.127 (844); 5 1.062 (10.2.2; 666). Microdureté Vickers 265 kg/mm2. Gris foncé en section polie, plages à zonage complexe dû à des variations de Cu/Fe. Réflectances maximales: 27.1 (420), 26.6 (500), 27.1 (540), 27.7 (600), 28.2 (660); 28.7 (700 nm). Giraudite, (Cu, Zn, Ag)12(As, Sb)4(Se, S)13. Cubique $$I\bar 43m$$ ,a=10.578 Å,Z=2; structure type tétraédrite. Analogue arsénié de la hakite. Densité calculée 5.75 g/cm3. Raies les plus intenses du diagramme de poudre: 10 3.050 (222); 5 2.497 (411; 330); 6 1.932 (521); 9 1.868 (440); 7 1.593 (622). Microdureté Vickers 293 kg/mm2. Gris clair, réflectances: 32.2 (420), 31.6 (500), 31.7 (540), 31.7 (600), 31.5 (660), 30.8 (700 nm). Trois épisodes minéralisants, séparés par des mouvements tectoniques, forment la paragenèse de Chaméane, comportant: barytine, pechblende, hématite, löllingite, mispickel, pyrite, chalcopyrite, clausthalite, tétraédrite, tennantite, bukovite, athabascaïte, umangite, berzelianite, klockmannite, eucaïrite, geffroyite, chaméanite, giraudite, eskebornite.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01084639
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