Wesselsite, SrCu[Si<sub>4</sub>O<sub>10</sub>], a further new gillespite-group mineral from the Kalahari Manganese Field, South Africa

Giester, Gerald; Rieck, Branko

doi:10.1180/minmag.1996.060.402.09

Cited by 22 publications

(9 citation statements)

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“…The phosphors have a tetragonal structure with refractive indices of 1.63 (ordinary ray, electric field perpendicular to the c-axis) and 1.59 (extraordinary ray). 2,19,20 Since the acrylic polymer has an index of $1.5, scattering is reduced relative to a powder in air, and the color is a darker blue. All the pigmented coating samples used in the current work were prepared at Berkeley Lab by hand-dispersing pigments into a transparent acrylic base (Liquitex gloss medium and varnish) with a spatula, which does not lead to an ideal dispersion.…”

Section: Sample Preparationmentioning

confidence: 99%

“…1 The strontium variant, SrCuSi 4 O 10 , is less known but is a similar blue pigment. 2 In 2000, Pozza et al 3 published photoluminescent spectra of Egyptian blue, Han blue, and Han purple (BaCuSi 2 O 6 ), and proposed that photoluminescence could be used to distinguish between Egyptian and Han blue in ancient works of art. Accorsi et al 4 provided more detailed information on the fluorescence of Egyptian blue and its application to artworks from ancient Egypt.…”

Section: Introductionmentioning

confidence: 99%

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High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

Berdahl

Boocock

Chan

et al. 2018

Journal of Applied Physics

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The alkaline earth copper tetra-silicates, blue pigments, are interesting infrared phosphors. The Ca, Sr, and Ba variants fluoresce in the near-infrared (NIR) at 909, 914, and 948 nm, respectively, with spectral widths on the order of 120 nm. The highest quantum yield / reported thus far is ca. 10%. We use temperature measurements in sunlight to determine this parameter. The yield depends on the pigment loading (mass per unit area) x with values approaching 100% as x ! 0 for the Ca and Sr variants. Although maximum quantum yield occurs near x ¼ 0, maximum fluorescence occurs near x ¼ 70 g m À2 , at which / ¼ 0.7. The better samples show fluorescence decay times in the range of 130 to 160 ls. The absorbing impurity CuO is often present. Good phosphor performance requires long fluorescence decay times and very low levels of parasitic absorption. The strong fluorescence enhances prospects for energy applications such as cooling of sunlit surfaces (to reduce air conditioning requirements) and luminescent solar concentrators.

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Section: Sample Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

Berdahl

Boocock

Chan

et al. 2018

Journal of Applied Physics

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“…Below and above this range they are, although difficult, feasible, albeit with a relatively large estimated error. Colinowensite is uniaxial (-) negative, with ω = 1.740 20, ε = 1.735 20 Calcium contents like those found in some crystals in previous work (Giester and Rieck, 1996) were not detected.…”

Section: Physical and Optical Propertiesmentioning

confidence: 58%

“…A comprehensive description of the so far 161 minerals -19 of which having their type locality in the regionis given by Cairncross and Beukes (2013). Over the last two decades, the mineralogy of this deposit has been subject to several studies at our Institute, resulting in the description of the new mineral species effenbergerite, BaCuSi 4 O 10 (Giester and Rieck, 1994), wesselsite, SrCuSi 4 O 10 (Giester and Rieck, 1996) and cairncrossite, Sr 2 Ca 7-x Na 2x (Si 4 O 10 ) 4 (OH) 2 • (H 2 O) 15-x (with x ∼0-1) (Giester et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Structure refinements on synthetic SrCuSi 4 O 10 were done by Rietveld analysis of neutron powder diffraction data (Chakoumakos et al, 1993;Knight et al, 2010). The first description of wesselsite (Giester and Rieck, 1996), had been based on powder XRD data due to the lack of appropriate single crystals. From EDX analyses of 111 samples it was evident that a solid (Knight and Henderson, 2007;Knight et al, 2010) proved complete miscibility in the wesselsite-effenbergerite solid solution series.…”

Section: Introductionmentioning

confidence: 99%

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Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

2015

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A new silicate, colinowensite, BaCuSi2O6, has been found in the Wessels mine, Kalahari Manganese Field, South Africa. It is associated with effenbergerite, wesselsite, lavinskyite, scottyite, diegogattaite, as well as with pectolite, quartz, aegirine, richterite, minerals of the garnet group and a number of different manganese and iron oxides, especially hausmannite and hematite. The mineral was named for the mineral collector and finder of the new species, Colin R. Owens, of Somerset West, South Africa. Colinowensite is brittle, with uneven fracture, and the estimated Mohs hardness is ∼4. It occurs as subhedral crystals <100 μm in size. The forms {100} and {110} are observed while {001} is always present in cleavage plates. The calculated density is 4.236 g cm–3. It is the natural analogue of the synthetic pigmentreferred to as Chinese or Han purple, which is found on artifacts from ancient and imperial China. The mineral is of dark blue to purple colour, with a purple streak, and is uniaxial (–), with ω = 1.740 (20), ε = 1.735 (20) (420 nm) and ω = 1.745 (20), ε = 1.730(20) (650 nm). The lustre is vitreous and no fluorescence is observed under either shortwave or longwave ultraviolet radiation. Avery strong pleochroism occurs from purple along the c axis to blue in a perpendicular direction. Colinowensite is not soluble in acids except HF. Electron microprobe analyses gave an average composition (wt.%) of CuO 22.53, BaO 43.43 and SiO2 34.04 yielding the empirical formula (based on 6 O a.p.f.u.) BaCuSi2O6. The new mineral is tetragonal, space group I41/acd with Z = 16, anda = 9.967(1), c = 22.290 (2) Å. Colinowensite is a cyclosilicate with [Si4O12]8– 4-membered single rings, arranged in sheets parallel to (001). The structure is further characterized by CuO4 squares sharing corners with four neighbouring silicate rings within a sheet. Ba2+ cations are bonded to ten O atoms in irregular coordination. Average Si–O, Cu–O and Ba–O bond lengths are 1.619, 1.934 and 2.943 Å, respectively. Colinowensite belongs to subdivision 9. CE of the Strunz Mineralogical Tables. In addition, based on single-crystal X-ray work, new structural data for wesselsite of chemical composition Sr0.9Ba0.1CuSi4O10 are provided.

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Hydrothermal Formation of Calcium Copper Tetrasilicate

Johnson-McDaniel

Comer

Kolis

et al. 2015

Chemistry A European J

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We describe the first hydrothermal synthesis of CaCuSi4 O10 as micron-scale clusters of thin platelets, distinct from morphologies generated under salt-flux or solid-state conditions. The hydrothermal reaction conditions are surprisingly specific: too cold, and instead of CaCuSi4 O10 , a porous calcium copper silicate forms; too hot, and calcium silicate (CaSiO3 ) forms. The precursors also strongly impact the course of the reaction, with the most common side product being sodium copper silicate (Na2 CuSi4 O10 ). Optimized conditions for hydrothermal CaCuSi4 O10 formation from calcium chloride, copper(II) nitrate, sodium silicate, and ammonium hydroxide are 350 °C at 3000 psi for 72 h; at longer reaction times, competitive delamination and exfoliation causes crystal fragmentation. These results illustrate that CaCuSi4 O10 is an even more unique material than previously appreciated.

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Wesselsite, SrCu[Si₄O₁₀], a further new gillespite-group mineral from the Kalahari Manganese Field, South Africa

Cited by 22 publications

References 7 publications

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

Hydrothermal Formation of Calcium Copper Tetrasilicate

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Wesselsite, SrCu[Si4O10], a further new gillespite-group mineral from the Kalahari Manganese Field, South Africa

Cited by 22 publications

References 7 publications

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

Colinowensite, BaCuSi2O6, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi4O10

Hydrothermal Formation of Calcium Copper Tetrasilicate

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Wesselsite, SrCu[Si₄O₁₀], a further new gillespite-group mineral from the Kalahari Manganese Field, South Africa

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀