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Redgillite, Cu (sub 6) (OH) (sub 10) (SO (sub 4) ).H (sub 2) O, a new mineral from Caldbeck Fells, Cumbria, England; description and crystal structure

J. J. Pluth, I. M. Steele, A. R. Kampf and D. I. Green
Redgillite, Cu (sub 6) (OH) (sub 10) (SO (sub 4) ).H (sub 2) O, a new mineral from Caldbeck Fells, Cumbria, England; description and crystal structure
Mineralogical Magazine (December 2005) 69 (6): 973-980

Abstract

Redgillite, Cu (sub 6) (OH) (sub 10) (SO (sub 4) ).H (sub 2) O, space group P2 (sub 1) /c, a 3.155(3) Aa, b 10.441(8) Aa, c 19.436(16) Aa, beta 90.089(13) degrees , V = 640.2(9) Aa (super 3) , Z = 2, is a new mineral from Silver Gill, Caldbeck Fells, Cumbria, England. The strongest six lines of the X-ray powder-diffraction pattern [d in Aa, (I) (hkl)] are: 9.72 (90) (002), 7.11 (100) (012), 4.60 (30) (022), 4.068 (20) (023), 2.880 (30) (112), 2.318 (50) (131). It occurs as translucent to transparent grass-green bladed crystals up to 0.15 mm long with squared-off or tapering terminations; usually in radiating groups. Forms observed are {001} prominent, {010} as composite stepped faces, and {100} irregular. Redgillite has white streak, vitreous lustre and Mohs hardness of approximately 2. Blades are slightly flexible with irregular fracture and exhibit a perfect {001} cleavage and good {100} and {010} cleavages. The measured density (by sink-float) is 3.45(5) g/cm (super 3) ; the calculated density is 3.450 g/cm (super 3) . The mineral dissolves slowly in dilute HCl. Redgillite is biaxial-negative with alpha = 1.693(2), beta = 1.721(2), gamma = 1.723(2), 2V = 30(2) degrees (meas.) and 30 degrees (calc.); dispersion is r > v, medium; pleochroism: Y blue-green>X blue-green>Z yellow-green; orientation: X nearly equal c, Y = b, Z nearly equal a. Electron microprobe analyses yielded CuO 68.9, SO (sub 3) 11.6, total 80.5. With water inferred from the structure analysis, the empirical formula is: Cu (sub 5.995) (OH) (sub 9.991) (SO (sub 4) ) (sub 1.003) . H (sub 2) O. Redgillite is typically found in thin fractures in partly oxidized sulphides where it is commonly associated with langite and more rarely with malachite, cuprite, connellite and brochantite. The name is for the Red Gill mine, from which the mineral is best known. The crystal structure of redgillite was determined and refined to R = 0.090 for 1529 observed reflections [I>2sigma (I)]. The redgillite structure consists of Jahn-Teller distorted CuO (sub 6) octahedra and SO (sub 4) tetrahedra. The octahedra share edges to form sheets that are zig-zag in cross section. The SO (sub 4) tetrahedra share an oxygen with the Cu layer and link the layers by hydrogen bonds to OH groups. The crystal structures of wroewolfeite, langite, posnjakite, spangolite and schulenbergite are similar to redgillite. They all contain edge sharing CuO (sub 6) layers connected to SO (sub 4) groups with the layers bridged via hydrogen bonds.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 69
Serial Issue: 6
Title: Redgillite, Cu (sub 6) (OH) (sub 10) (SO (sub 4) ).H (sub 2) O, a new mineral from Caldbeck Fells, Cumbria, England; description and crystal structure
Affiliation: University of Chicago, Department of Geophysical Sciences, Chicago, United States
Pages: 973-980
Published: 200512
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 13
Accession Number: 2006-034871
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N54°04'60" - N55°15'00", W03°40'00" - W02°10'00"
Secondary Affiliation: Natural History Museum of Los Angeles County, USA, United StatesUniversity of Manchester, GBR, United Kingdom
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: 200619
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