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Canutite, NaMn (sub 3) [AsO (sub 4) ][AsO (sub 3) (OH)] (sub 2) , a new protonated alluaudite-group mineral from the Torrecillas Mine, Iquique Province, Chile

A. R. Kampf, S. J. Mills, F. Hatert, B. P. Nash, M. Dini and A. A. Molina Donoso
Canutite, NaMn (sub 3) [AsO (sub 4) ][AsO (sub 3) (OH)] (sub 2) , a new protonated alluaudite-group mineral from the Torrecillas Mine, Iquique Province, Chile
Mineralogical Magazine (August 2014) 78 (4): 787-795

Abstract

The new mineral canutite (IMA2013-070), NaMn (sub 3) [AsO (sub 4) ][AsO (sub 3) (OH)] (sub 2) , was found at two different locations at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, halite, lavendulan, magnesiokoritnigite, pyrite, quartz and scorodite. Canutite is reddish brown in colour. It forms as prisms elongated on [201i] and exhibiting the forms {010}, {100}, {102}, {201} and {102i}, or as tablets flattened on {102} and exhibiting the forms {102} and {110}. Crystals are transparent with a vitreous lustre. The mineral has a pale tan streak, Mohs hardness of 2 1/2, brittle tenacity, splintery fracture and two perfect cleavages, on {010} and {101}. The calculated density is 4.112 g cm (super -3) . Optically, canutite is biaxial (+) with alpha = 1.712(3), beta = 1.725(3) and gamma = 1.756(3) (measured in white light). The measured 2V is 65.6(4) degrees , the dispersion is r < v (slight), the optical orientation is Z = b; X ^ a = 18 degrees in obtuse beta and pleochroism is imperceptible. The mineral is slowly soluble in cold, dilute HCl. The empirical formula (for tabular crystals from near the mine shaft), determined from electron-microprobe analyses, is (Na (sub 1.05) Mn (sub 2.64) Mg (sub 0.34) Cu (sub 0.14) Co (sub 0.03) ) (sub Sigma 4.20) As (sub 3) O (sub 12) H (sub 1 .62) . Canutite is monoclinic, C2/c, a = 12.3282(4), b = 12.6039(5), c = 6.8814(5) Aa, beta = 113.480(8) degrees , V = 980.72(10) Aa (super 3) and Z = 4. The eight strongest X-ray powder diffraction lines are [d (sub obs) Aa(I)(hkl)]: 6.33(34)(020), 4.12(26)(2i1), 3.608(29)(310,1i31), 3.296(57)(1i12), 3.150(28)(002,131), 2.819(42)(400,041,330), 2.740(100)(240,4i02,112) and 1.5364(31)(multiple). The structure, refined to R (sub 1) = 2.33% for 1089 F (sub o) > 4sigma F reflections, shows canutite to be isostructural with protonated members of the alluaudite group.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 78
Serial Issue: 4
Title: Canutite, NaMn (sub 3) [AsO (sub 4) ][AsO (sub 3) (OH)] (sub 2) , a new protonated alluaudite-group mineral from the Torrecillas Mine, Iquique Province, Chile
Affiliation: Natural History Museum of Los Angeles County, Mineral Sciences Department, Los Angeles, CA, United States
Pages: 787-795
Published: 201408
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 23
Accession Number: 2015-002461
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
S21°30'00" - S19°00'00", W70°15'00" - W68°30'00"
Secondary Affiliation: Museum Victoria, AUS, AustraliaUniversite de Liege, BEL, BelgiumUniversity of Utah, USA, United States
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201502
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