Rruffite, Ca2Cu(AsO4)2·2H 2O, a new member of the roselite group, from Tierra Amarilla, Chile

Hexiong Yang, Robert A. Jenkins, Robert T Downs, Stanley H. Evans, Kimberly T. Tait

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

A new mineral species, rruffite, ideally Ca2Cu(AsO 4)2·2H2O, has been found in the oxidation zone of the Cu-As orebody in the Maria Catalina mine, Tierra Amarilla, Chile. It is a secondary mineral and occurs in granular or blocky aggregates and druses. Associated minerals include quartz, barite, mansfieldite, alumopharmacosiderite, conichalcite, metazeunerite, and barahonite-(Al). Rruffite is pale or light blue, transparent with white streak and vitreous luster. It is brittle, has a Mohs hardness of ∼3 and a perfect cleavage on {010}, and is twinned on (100). The measured and calculated densities are 3.79(3) and 3.77(2) g/cm3, respectively. Rruffite is insoluble in water, acetone, and hydrochloric acid. Optically, it is biaxial (-), with α 1.725(1), β 1.734(1), γ 1.740(1), 2Vmeas 80(2)°, Y= b, X ∧ c 49°, and it does not fluoresce under long-or short-wave ultraviolet light. The dispersion is weak, with r < v. An electron-microprobe analysis yielded the empirical formula Ca 2.01Cu1.01(AsO4)2.02·1. 9H2O. Rruffite, isostructural with roselite, is monoclinic, with space group P21/c and unit-cell parameters a 5.8618(2), b 12.7854(5), c 5.7025 (2) Å, β 109.425(2)°, and V 403.05(3) Å3. Its structure is characterized by isolated CuO 4(H2O)2 octahedra that are linked by corner-sharing with ASO4 tetrahedra to form the krohnkite-type chains parallel to the c axis. These chains are linked together by large Ca cations and hydrogen bonding. Owing to the strong Jahn-Teller effect, the MO 4(H2O)2 octahedron in rruffite is the most distorted of all known roselite-group minerals (M = Cu, Co, Mn, Mg, and Zn) in terms of the quadratic elongation of the octahedra. The Raman spectra of rruffite resemble those of arsenate minerals of the roselite group.

Original languageEnglish (US)
Pages (from-to)877-884
Number of pages8
JournalCanadian Mineralogist
Volume49
Issue number3
DOIs
StatePublished - Jun 2011

Fingerprint

Minerals
mineral
Arsenate minerals
new mineral
secondary mineral
barite
arsenate
Barium Sulfate
hydrochloric acid
acetone
Jahn-Teller effect
electron probe analysis
cleavage
Quartz
hardness
Hydrochloric Acid
Electron probe microanalysis
Acetone
cation
hydrogen

Keywords

  • Arsenate
  • Chile
  • Crystal structure
  • Raman spectra
  • Roselite
  • Rruffite
  • Tierra Amarilla
  • X-ray diffraction

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Rruffite, Ca2Cu(AsO4)2·2H 2O, a new member of the roselite group, from Tierra Amarilla, Chile. / Yang, Hexiong; Jenkins, Robert A.; Downs, Robert T; Evans, Stanley H.; Tait, Kimberly T.

In: Canadian Mineralogist, Vol. 49, No. 3, 06.2011, p. 877-884.

Research output: Contribution to journalArticle

Yang, Hexiong ; Jenkins, Robert A. ; Downs, Robert T ; Evans, Stanley H. ; Tait, Kimberly T. / Rruffite, Ca2Cu(AsO4)2·2H 2O, a new member of the roselite group, from Tierra Amarilla, Chile. In: Canadian Mineralogist. 2011 ; Vol. 49, No. 3. pp. 877-884.
@article{8013294c3aee4fedb5bfd19351d47b1e,
title = "Rruffite, Ca2Cu(AsO4)2·2H 2O, a new member of the roselite group, from Tierra Amarilla, Chile",
abstract = "A new mineral species, rruffite, ideally Ca2Cu(AsO 4)2·2H2O, has been found in the oxidation zone of the Cu-As orebody in the Maria Catalina mine, Tierra Amarilla, Chile. It is a secondary mineral and occurs in granular or blocky aggregates and druses. Associated minerals include quartz, barite, mansfieldite, alumopharmacosiderite, conichalcite, metazeunerite, and barahonite-(Al). Rruffite is pale or light blue, transparent with white streak and vitreous luster. It is brittle, has a Mohs hardness of ∼3 and a perfect cleavage on {010}, and is twinned on (100). The measured and calculated densities are 3.79(3) and 3.77(2) g/cm3, respectively. Rruffite is insoluble in water, acetone, and hydrochloric acid. Optically, it is biaxial (-), with α 1.725(1), β 1.734(1), γ 1.740(1), 2Vmeas 80(2)°, Y= b, X ∧ c 49°, and it does not fluoresce under long-or short-wave ultraviolet light. The dispersion is weak, with r < v. An electron-microprobe analysis yielded the empirical formula Ca 2.01Cu1.01(AsO4)2.02·1. 9H2O. Rruffite, isostructural with roselite, is monoclinic, with space group P21/c and unit-cell parameters a 5.8618(2), b 12.7854(5), c 5.7025 (2) {\AA}, β 109.425(2)°, and V 403.05(3) {\AA}3. Its structure is characterized by isolated CuO 4(H2O)2 octahedra that are linked by corner-sharing with ASO4 tetrahedra to form the krohnkite-type chains parallel to the c axis. These chains are linked together by large Ca cations and hydrogen bonding. Owing to the strong Jahn-Teller effect, the MO 4(H2O)2 octahedron in rruffite is the most distorted of all known roselite-group minerals (M = Cu, Co, Mn, Mg, and Zn) in terms of the quadratic elongation of the octahedra. The Raman spectra of rruffite resemble those of arsenate minerals of the roselite group.",
keywords = "Arsenate, Chile, Crystal structure, Raman spectra, Roselite, Rruffite, Tierra Amarilla, X-ray diffraction",
author = "Hexiong Yang and Jenkins, {Robert A.} and Downs, {Robert T} and Evans, {Stanley H.} and Tait, {Kimberly T.}",
year = "2011",
month = "6",
doi = "10.3749/canmin.49.3.877",
language = "English (US)",
volume = "49",
pages = "877--884",
journal = "Canadian Mineralogist",
issn = "0008-4476",
publisher = "Mineralogical Association of Canada",
number = "3",

}

TY - JOUR

T1 - Rruffite, Ca2Cu(AsO4)2·2H 2O, a new member of the roselite group, from Tierra Amarilla, Chile

AU - Yang, Hexiong

AU - Jenkins, Robert A.

AU - Downs, Robert T

AU - Evans, Stanley H.

AU - Tait, Kimberly T.

PY - 2011/6

Y1 - 2011/6

N2 - A new mineral species, rruffite, ideally Ca2Cu(AsO 4)2·2H2O, has been found in the oxidation zone of the Cu-As orebody in the Maria Catalina mine, Tierra Amarilla, Chile. It is a secondary mineral and occurs in granular or blocky aggregates and druses. Associated minerals include quartz, barite, mansfieldite, alumopharmacosiderite, conichalcite, metazeunerite, and barahonite-(Al). Rruffite is pale or light blue, transparent with white streak and vitreous luster. It is brittle, has a Mohs hardness of ∼3 and a perfect cleavage on {010}, and is twinned on (100). The measured and calculated densities are 3.79(3) and 3.77(2) g/cm3, respectively. Rruffite is insoluble in water, acetone, and hydrochloric acid. Optically, it is biaxial (-), with α 1.725(1), β 1.734(1), γ 1.740(1), 2Vmeas 80(2)°, Y= b, X ∧ c 49°, and it does not fluoresce under long-or short-wave ultraviolet light. The dispersion is weak, with r < v. An electron-microprobe analysis yielded the empirical formula Ca 2.01Cu1.01(AsO4)2.02·1. 9H2O. Rruffite, isostructural with roselite, is monoclinic, with space group P21/c and unit-cell parameters a 5.8618(2), b 12.7854(5), c 5.7025 (2) Å, β 109.425(2)°, and V 403.05(3) Å3. Its structure is characterized by isolated CuO 4(H2O)2 octahedra that are linked by corner-sharing with ASO4 tetrahedra to form the krohnkite-type chains parallel to the c axis. These chains are linked together by large Ca cations and hydrogen bonding. Owing to the strong Jahn-Teller effect, the MO 4(H2O)2 octahedron in rruffite is the most distorted of all known roselite-group minerals (M = Cu, Co, Mn, Mg, and Zn) in terms of the quadratic elongation of the octahedra. The Raman spectra of rruffite resemble those of arsenate minerals of the roselite group.

AB - A new mineral species, rruffite, ideally Ca2Cu(AsO 4)2·2H2O, has been found in the oxidation zone of the Cu-As orebody in the Maria Catalina mine, Tierra Amarilla, Chile. It is a secondary mineral and occurs in granular or blocky aggregates and druses. Associated minerals include quartz, barite, mansfieldite, alumopharmacosiderite, conichalcite, metazeunerite, and barahonite-(Al). Rruffite is pale or light blue, transparent with white streak and vitreous luster. It is brittle, has a Mohs hardness of ∼3 and a perfect cleavage on {010}, and is twinned on (100). The measured and calculated densities are 3.79(3) and 3.77(2) g/cm3, respectively. Rruffite is insoluble in water, acetone, and hydrochloric acid. Optically, it is biaxial (-), with α 1.725(1), β 1.734(1), γ 1.740(1), 2Vmeas 80(2)°, Y= b, X ∧ c 49°, and it does not fluoresce under long-or short-wave ultraviolet light. The dispersion is weak, with r < v. An electron-microprobe analysis yielded the empirical formula Ca 2.01Cu1.01(AsO4)2.02·1. 9H2O. Rruffite, isostructural with roselite, is monoclinic, with space group P21/c and unit-cell parameters a 5.8618(2), b 12.7854(5), c 5.7025 (2) Å, β 109.425(2)°, and V 403.05(3) Å3. Its structure is characterized by isolated CuO 4(H2O)2 octahedra that are linked by corner-sharing with ASO4 tetrahedra to form the krohnkite-type chains parallel to the c axis. These chains are linked together by large Ca cations and hydrogen bonding. Owing to the strong Jahn-Teller effect, the MO 4(H2O)2 octahedron in rruffite is the most distorted of all known roselite-group minerals (M = Cu, Co, Mn, Mg, and Zn) in terms of the quadratic elongation of the octahedra. The Raman spectra of rruffite resemble those of arsenate minerals of the roselite group.

KW - Arsenate

KW - Chile

KW - Crystal structure

KW - Raman spectra

KW - Roselite

KW - Rruffite

KW - Tierra Amarilla

KW - X-ray diffraction

UR - http://www.scopus.com/inward/record.url?scp=80052500977&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80052500977&partnerID=8YFLogxK

U2 - 10.3749/canmin.49.3.877

DO - 10.3749/canmin.49.3.877

M3 - Article

AN - SCOPUS:80052500977

VL - 49

SP - 877

EP - 884

JO - Canadian Mineralogist

JF - Canadian Mineralogist

SN - 0008-4476

IS - 3

ER -