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Leverettite from the Torrecillas Mine, Iquique Province, Chile; the Co-analogue of herbertsmithite

A. R. Kampf, M. J. Sciberras, P. A. Williams, M. Dini and A. A. Molina Donoso
Leverettite from the Torrecillas Mine, Iquique Province, Chile; the Co-analogue of herbertsmithite
Mineralogical Magazine (October 2013) 77 (7): 3047-3054

Abstract

The new mineral leverettite (IMA 2013-011), ideally Cu (sub 3) CoCl (sub 2) (OH) (sub 6) , was found at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a supergene alteration phase in association with akaganeite, anhydrite, chalcophanite, goethite, halite, manganite, pyrite, quartz and todorokite. Crystals of leverettite are steep rhombohedra to 1 mm with {101} prominent and modified by {001}, sometimes forming V-shaped twins by reflection on {102I}. The crystals can also form finger-like, parallel stacked growths along the c axis. The new mineral is medium to deep green in colour and has a light green streak. Crystals are transparent with a vitreous lustre. Mohs hardness is approximately 3 and the crystals have a brittle tenacity, a perfect cleavage on {101} and a conchoidal fracture. The measured density is 3.64(2) g cm (super -3) and calculated density based on the empirical formula is 3.709 g cm (super -3) . Optically, leverettite is uniaxial (-) with omega and epsilon > 1.8 and exhibits pleochroism with O (bluish green) > E (slightly yellowish green). The empirical formula, determined from electron-microprobe analyses is Cu (sub 3) (Co (sub 0.43) Cu (sub 0.40) Mn (sub 0.17) Ni (sub 0.07) Mg (sub 0.01) ) (sub Sigma 1.08) Cl (sub 1.8 7) O (sub 6.13) H (sub 6) . Leverettite is trigonal (hexagonal), space group R3Im, unit-cell parameters a = 6.8436(6) and c = 14.064(1) Aa, V = 570.42(8) Aa (super 3) , Z = 3. The eight strongest X-ray powder diffraction lines are [d (sub obs) Aa(I)(hkl)]: 5.469(90)(101), 4.701(18)(003), 2.905(22)(021), 2.766(100)(113), 2.269(66)(024), 1.822(26)(033), 1.711(33)(220), 1.383(23)(128). The structure, refined to R (sub 1) = 0.023 for 183 F (sub o) > 4sigma F reflections, shows leverettite to be isostructural with herbertsmithite and gillardite.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 77
Serial Issue: 7
Title: Leverettite from the Torrecillas Mine, Iquique Province, Chile; the Co-analogue of herbertsmithite
Affiliation: Natural History Museum of Los Angeles County, Mineral Sciences Department, Los Angeles, CA, United States
Pages: 3047-3054
Published: 201310
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 14
Accession Number: 2013-091424
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
S20°58'13" - S20°58'13", W70°08'17" - W70°08'17"
Secondary Affiliation: University of Western Sydney, AUS, Australia
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: 201353
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