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Protocaseyite, a new decavanadate mineral containing a [Al (sub 4) (OH) (sub 6) (H (sub 2) O) (sub 12) ] (super 6+) linear tetramer, a novel isopolycation

Anthony R. Kampf, Mark A. Cooper, John M. Hughes, Chi Ma, William H. Casey, Frank C. Hawthorne and Joe Marty
Protocaseyite, a new decavanadate mineral containing a [Al (sub 4) (OH) (sub 6) (H (sub 2) O) (sub 12) ] (super 6+) linear tetramer, a novel isopolycation
American Mineralogist (June 2022) 107 (6): 1181-1189

Abstract

Protocaseyite, [Al (sub 4) (OH) (sub 6) (H (sub 2) O) (sub 12) ][V (sub 10) O (sub 28) ].8H (sub 2) O, is a new mineral (IMA2020-090) occurring in low-temperature, post-mining, secondary mineral assemblages at the Burro mine, Slick Rock district, San Miguel County, Colorado, U.S.A. Crystals of protocaseyite are saffron-yellow, thick blades, with pale orange-yellow streak, vitreous luster, brittle tenacity, curved fracture, two very good cleavages, a Mohs hardness of 2, and a density of 2.45(2) g/cm (super 3) . The optical properties of protocaseyite could be only partly determined: biaxial with alpha =1.755(5), beta <1.80, gamma >1.80 (white light); pleochroic with X and Y yellow, Z orange (X nearly equal Y<Z). Electron-probe microanalysis and crystal-structure solution and refinement provided the empirical formula [(Al (sub 3.89) Mg (sub 0.11) Ca (sub 0.02) ) (sub Sigma 4.02) (OH) (sub 6) (H (sub 2) O) (sub 12) ] [H (sub 0.06) V (sub 10) O (sub 28) ].8H (sub 2) O. Protocaseyite is triclinic, P1, a=9.435(2), b=10.742(3), c=11.205(3) Aa, alpha =75.395(7), beta =71.057(10), gamma =81.286(6) degrees , V=1036.4(5) Aa3, and Z=1. The crystal structure (R (sub 1) =0.026 for 4032 I (sub o) >2 sigma I reflections) contains both the [V (sub 10) O (sub 28) ] (super 6-) decavanadate polyoxoanion and a novel [Al (sub 4) (OH) (sub 6) (H (sub 2) O) (sub 12) ] (super 6+) polyoxocation.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 107
Serial Issue: 6
Title: Protocaseyite, a new decavanadate mineral containing a [Al (sub 4) (OH) (sub 6) (H (sub 2) O) (sub 12) ] (super 6+) linear tetramer, a novel isopolycation
Affiliation: Natural History Museum of Los Angeles County, Mineral Sciences Department, Los Angeles, CA, United States
Pages: 1181-1189
Published: 202206
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 42
Accession Number: 2022-033441
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N37°47'60" - N38°07'60", W109°01'60" - W107°45'00"
Secondary Affiliation: University of Manitoba, CAN, CanadaUniversity of Vermont, USA, United StatesCalifornia Institute of Technology, USA, United StatesUniversity of California at Davis, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202212
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