New naturally occurring mineral phases from the Krásno - Horní Slavkov area, western Bohemia, Czech Republic

Sejkora, Jiří; Škoda, Radek; Ondruš, Petr

doi:10.3190/jcgs.992

Cited by 13 publications

(13 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Further unnamed Zn-Fe 3+ and Fe 2+ -Al phosphate members of the arthurite group were also reported by Sejkora et al (2006) from Krásno, Czech Republic. The latter phase (''UNK8''; Sejkora et al 2006) forms as tiny zones (up to 40 mm) within kunatite crystals (the presence of divalent iron in this phase is deduced from stoichiometry). A possible Mn 2+ -Mn 3+ -As member from Falotta, Switzerland, which forms small red crystals, is mentioned on http://homepage.swissonline.ch/KlingerMinerals/mineralienfalotta-e.htm.…”

Section: X-ray Diffraction and Crystal Structurementioning

confidence: 71%

Bendadaite, a new iron arsenate mineral of the arthurite group

et al. 2010

View full text Add to dashboard Cite

Bendadaite, ideally Fe2+Fe23+(AsO4)2(OH)2·4H2O, is a new member of the arthurite group. It was found as a weathering product of arsenopyrite on a single hand specimen from the phosphate pegmatite Bendada, central Portugal (type locality). Co-type locality is the granite pegmatite of Lavra do Almerindo (Almerindo mine), Linópolis, Divino das Laranjeiras county, Minas Gerais, Brazil. Further localities are the Veta Negra mine, Copiapó province, Chile; Oumlil-East, Bou Azzer district, Morocco; and Pira Inferida yard, Fenugu Sibiri mine, Gonnosfanadiga, Medio Campidano Province, Sardinia, Italy.Type bendadaite occurs as blackish green to dark brownish tufts (<0.1 mm long) and flattened radiating aggregates, in intimate association with an intermediate member of the scorodite–mansfieldite series. It is monoclinic, space groupP21/c, witha= 10.239(3) Å,b= 9.713(2) Å,c= 5.552(2) Å, β = 94.11(2)°,V= 550.7(2) Å3, Z = 2. Electron-microprobe analysis yielded (wt.%): CaO 0.04, MnO 0.03, CuO 0.06, ZnO 0.04, Fe2O3(total) 43.92, Al2O31.15, SnO20.10, As2O543.27, P2O51.86, SO30.03. The empirical formula is (Fe2+0.52Fe3+0.32☐0.16)Σ1.00(Fe3+1.89Al0.11)Σ2.00(As1.87P0.13)Σ2.00O8(OH)2.00·4H2O based on 2(As,P) and assuming ideal 8O, 2(OH), 4H2O and complete occupancy of the ferric iron site by Fe3+and Al. Optically, bendadaite is biaxial, positive, 2Vest.= 85±4°, 2Vcalc.= 88°, with α 1.734(3), β 1.759(3), γ 1.787(4). Pleochroism is medium strong:Xpale reddish brown,Yyellowish brown,Zdark yellowish brown; absorptionZ>Y>X, optical dispersion weak,r>v. Optical axis plane is parallel to (010), withXapproximately parallel toaandZnearly parallel to c. Bendadaite has vitreous to sub-adamantine luster, is translucent and non-fluorescent. It is brittle, shows irregular fracture and a good cleavage parallel to {010}. Dmeas.3.15±0.10 g/cm3, Dcalc.3.193 g/cm3(for the empirical formula). The five strongest powder diffraction lines [din Å (I)(hkl)] are 10.22 (10)(100), 7.036 (8)(110), 4.250 (5)(111), 2.865 (4)(), 4.833 (3)(020,011). Thedspacings are very similar to those of its Zn analogue, ojuelaite. The crystal structure of bendadaite was solved and refined using a crystal from the co-type locality with the composition (Fe2+0.95☐0.05)Σ1.00(Fe3+1.80Al0.20)Σ2.00(As1.48P0.52)Σ2.00O8(OH)2·4H2O (R= 1.6%), and confirms an arthurite-type atomic arrangement.

show abstract

Section: X-ray Diffraction and Crystal Structurementioning

confidence: 71%

Bendadaite, a new iron arsenate mineral of the arthurite group

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Triclinic mineral turquoise belongs to a turquoise group; general formula for minerals of this group may be written as A 0-1 B 6 (PO 4 ) 4 (OH) 8 Á4H 2 O. Most common substituents at the A position are Cu 2+ , Fe 2+ Zn 2+ or vacancy; at the B position then Al 3+ or Fe 3+ [4,[36][37][38].…”

Section: Background Informationmentioning

confidence: 99%

Raman and infrared spectroscopic study of turquoise minerals

Čejka

Sejkora

Macek

et al. 2015

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

View full text Add to dashboard Cite

Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed.

show abstract

“…Samples of krásnoite were found at the abandoned Huber open pit (50º07'21.28'' N, 12º47'59.15'' E), Krá sno ore district near Horní Slavkov, Slavkovský les mountains, western Bohemia, Czech Republic (Sejkora et al, 2006a). Krásnoite occurs in strongly altered areas (Sejkora et al, 2006b), which range in size from 1 cm to 10 cm across.…”

Section: Occurrence and Paragenesis Krá Snomentioning

confidence: 99%

“…Both groups had also previously noted the new mineral reported herein. Sejkora et al (2006a) first reported 13 EMPA analyses, with powder X-ray diffraction data, on unnamed mineral UNK1 from Krá sno, which they described as a possible F-analogue of perhamite. The same phase was also noted at the Silver Coin mine, during the investigations which led to the description of meurigite-Na (Kampf et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Krásnoite, the fluorophosphate analogue of perhamite, from the Huber open pit, Czech Republic and the Silver Coin mine, Nevada, USA

et al. 2012

Self Cite

View full text Add to dashboard Cite

Krásnoite is a new mineral (IMA2011-040) from the Huber open pit, Krásno ore district, Czech Republic and the Silver Coin mine, Nevada, USA. Krásnoite is the fluorophosphate analogue of perhamite. Krásnoite occurs as compact to finely crystalline aggregates, balls and rosette-like clusters up to 1 mm across. Individual crystals are platy, show a hexagonal outline and can reach 0.1 mm on edge at Krásno and 0.4 mm at Silver Coin. At both localities, krásnoite occurs very late in phosphaterich paragenetic sequences. Krásnoite crystals are partly transparent with a typically pearly lustre, but can also appear greasy (Krásno) or dull (Silver Coin). The streak is white and the hardness is 5 on the Mohs scale. Crystals are brittle, have an irregular fracture, one imperfect cleavage on {001} and are not fluorescent under SW and LW ultraviolet light. Penetration twinning ⊥ {001} is common. The density for both Krásno and Silver Coin material is 2.48(4) g cm–3, measured by the sink–float method in an aqueous solution of sodium polytungstate. The calculated density is 2.476 g cm–3 (Krásno). Krásnoite crystals are uniaxial (+), with ω = 1.548(2) and ε = 1.549(2) (Krásno) and ω = 1.541(1) and ε = 1.543(1) (Silver Coin). The simplified formula of krásnoite is: Ca3Al7.7Si3P4O23.5(OH)12.1F2·8H2O. Krásnoite is trigonal, space group Pm1, with a = 6.9956(4), c = 20.200(2) Å, V = 856.09(9) Å3 and Z = 3. Raman and infrared spectroscopy, coupled with magic-angle spinning nuclear magnetic resonance (MAS–NMR) spectrometry, confirmed the presence of PO3F, PO4, SiO4, H2O and OH in the crystal structure of krásnoite.

show abstract

New naturally occurring mineral phases from the Krásno - Horní Slavkov area, western Bohemia, Czech Republic

Cited by 13 publications

References 14 publications

Bendadaite, a new iron arsenate mineral of the arthurite group

Bendadaite, a new iron arsenate mineral of the arthurite group

Raman and infrared spectroscopic study of turquoise minerals

Krásnoite, the fluorophosphate analogue of perhamite, from the Huber open pit, Czech Republic and the Silver Coin mine, Nevada, USA

Contact Info

Product

Resources

About