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A crystal from the type locality Ajo, AZ, yielded just enough intensity from streaked diffractions using synchrotron x-rays at the Advanced Photon Source to solve the crystal structure with composition (K + Na) 3 Cu 20 Al 3 Si 29 O 76 (OH) 16 ⋅∼8H 2 O; triclinic, P1̄, a = 13.634(5) Å, b = 13.687(7), c = 14.522(7), α = 110.83(1)°, β = 107.21(1), γ = 105.68(1); refined to a final R = 12.5%. Electron microprobe analysis yielded a similar chemical composition that is slightly different from the combined chemical and electron microprobe analyses in the literature. The ajoite structure can be described as a zeolitic octahedral-tetrahedral framework that combines the alternate stacking of edge-sharing octahedral CuO 6 layers and curved aluminosilicate layers and strings. Channels bounded by elliptical 12-rings and circular 8-rings of tetrahedra contain (K and Na) ions and water. The Al atoms occupy some of the Si tetrahedral sites. Each Cu atom has near-planar bonds to four oxygen atoms plus two longer distances that generate a distorted octahedron. Valence bond estimates indicate that 8 oxygen atoms of 46 are hydroxyl. Only one alkali atom was located in distorted octahedral coordination, and electron microprobe analyses indicate K and Na as major substituents. The water from chemical analysis presumably occurs as disordered molecules of zeolitic type not giving electron density from diffraction. The high R factor results from structural disorder and many weak intensities close to detection level. The crystal chemistry is compared with shattuckite, Cu 5 (SiO 3 ) 4 (OH) 2 , and planchéite, Cu 8 Si 8 O 22 (OH) 4 ⋅H 2 O, both found in oxidized copper deposits of Arizona but only the former directly with ajoite.

A unique Cu-bearing chain silicate, Li2(Mg,Cu)Cuz[Si206b was synthesized, and the structure was determined by single-cry~tal X-ray diffraction techniques. The structure was found to be triclinic, spacoe group PI, with unit-cell parameters a = 5.7068(7), b = 7.4784(9), c = 5.2193(3) A, ex = 99.911(8), J3 = 97.436(8), 'Y = 84.52(1)°, and Z = 1. The arrangement of zweier single chains, [Siz06], differs significantly from chain arrangements in the pyroxene and pyroxenoid structures, and the "I-beam" description of the pyroxene structure is not applicable. The structure may be classified as a new derivative type of the pyroxene structure, with an "oblique I-beam". Cu atoms are coordinated by four ° atoms in a square-planar arrangement with 1.94-2.00 A for Cu-O and two ° atoms with longer Cu-O distances of 2.41-2.92 A, consistent with the crystal-field stabilization ~f the d9.electroni~ structure of Cu2+. The square-planar Cu04 units form a [CunOZn+2] nbbon with n = 3 ill the structure, which is also found in Cu-bearing chain silicates such as shattuckite and plancheite with n > 3. Mg is octahedrally coordinated by ° atoms, but the configuration is affected by the partial replacement by Cu.

Using reflection extended X-ray absorption fine structure spectroscopy (REFLEXAFS) and X-ray photoelectron spectroscopy (XPS) it has been established that Cu(II) in low concentration in aqueous media can be chemisorbed onto the (0001) surface of muscovite mica. From the XPS studies it is suggested that the Cu species is in a similar bonding environment to the copper in copper hydroxide. A depth profile of the reacted mica surface was also carried out using XPS and this suggests that there had been no diffusion of the Cu into the mica surface. REFLEXAFS studies of the reacted mica surface provided information about shells of O, Al/Si, and Cu surrounding a central Cu absorber. The best-fit bond distances are as follows: O–Cu, 1.98 A; Cu–Cu, 2.64 A; Al/Si–Cu, 3.09 A. This provides direct evidence for Cu being bound to the surface at aluminate or silicate groups and suggests that the Cu species adsorbed onto the surface are similar to the copper species found in copper hydroxide, plancheite, and shattuckite. It is proposed that Cu is chemisorbed at atomic imperfections, such as steps and kinks, on the mica surface.

Copper minerals (chrysocolla ≫ dioptase ≫ plancheite > tenorite) plus barite and quartz occur in a small lens of granulite- grade calcite-dolomite marble near Saldán, Córdoba Province (central Argentina, 31°18′50.7″S, 64°19′50.0″W). The mineralization is hosted in fractures (striking N30°E and dipping 78°W) that were widened by dissolution. Chrysocolla mainly fills fractures. It has variable H2O contents but the Cu:Si ratio is always close to 1: 1. Plancheite forms compact fissure fillings and aggregates of interlocking spherules. Copper is partially replaced by Mg (up to 2.22 wt. % MgO), with small amounts of Na, K, Ca, Al and Fe also present. Dioptase occurs as prismatic crystals dominated by {10 10} and {11 21} that can reach over 2 cm in length, and also as granular fracture fillings. Unit-cell parameters are a 14.5719(6), c 7.7799(3) Å, V 1430.7(1) Å3; refractive indices are ε = 1.707(3), ω = 1.656(3), with an anomalous small 2V. Magnesium (up to 0.15 wt. % MgO) is the only significant substituent. Yellow barite crystals tabular on {001} contain traces of Sr. Quartz occurs rarely, as drusy linings. A few cases of botryoidal, opal-like quartz crusts are known. Tenorite forms dark brown masses and stringers included in marble. Very scarce grains of copper sulfides (anilite altering to spionkopite and covellite along rims and cracks) are found scattered in the marble. Copper is partially replaced by Bi (≤ 0.15 wt. % Bi) and Pb (≤ 0.16 wt. % Pb). Malachite and brochantite are alteration products of sulfides. Fluid inclusion studies indicate that the minerals precipitated from a single-phase fluid initially at a temperature above 300°C that cooled to c. 220°C. Salinity was very low, 0 to 2 wt. % NaCl eq. Isotopic analyses of calcite give δ13C values of 0.4-0.9 ‰ PDB and δ18O values of 17.1-15.1 ‰ VSMOW, coincident with the isotopic signature of the regional marbles. Calculated values of δ18O for water in isotopic equilibrium with calcite fall into with the Metamorphic Water Box. The δ34S values of barite are 3.6-4.6 ‰ CDT. The mineralization possibly precipitated from fluids of meteoric origin that suffered an oxygen isotope shift due to a very low water/rock ratio. The sulfur source could have been sedimentary or igneous sulfides, or a mixture from two different sources (such as heavy seawater-derived sulfur and light sedimentary sulfides), but not exclusively seawater. Copper was probably scavenged from accessory sulfides scattered in barren marble or orthoamphibolite. The heat source remains unknown. Fil: Colombo, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Lira, Raul. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Museo de Geología y Miner.; Argentina Fil: Ripley, Edward. Indiana University; Estados Unidos Fil: González del Tánago, José. Universidad Complutense de Madrid; España

Shattuckite Cu(5)(SiO(3))(4)(OH)(2) is a copper hydroxy silicate and is commonly known as a 'healing' mineral. Three shattuckite mineral samples from three different origins were analysed by Raman spectroscopy. Some Raman bands are common in the spectra of the minerals. Raman bands at around 890, 1058 and 1102 are described as the ν(3) -SiO(3) antisymmetric stretching vibrations. The Raman band at 670cm(-1) is assigned to the ν(4) bending modes of the -SiO(3) units and the band at around 785cm(-1)is due to Si-O-Si chain stretching mode. Raman (and infrared) spectroscopy proves that water is in the molecular structure of shattuckite; thus the formula is better written as Cu(5)(SiO(3))(4)(OH)(2)·xH(2)O.

The aim of this study is to characterize pictorial pigments discovered in August 1984 by architects and archaeologists of the «Mission permanente» of CNRS in Karnak, Egypt. Described as parts of a painter's palette, these colouring matters include blue, red, white, green, and yellow pigmentsTTheir characterizations have been done using classic methods in physics applied to archaeology : SEM to observe faciès and textures, EDS for elemental analyses and X ray diffraction for cristallographie analyses. Results show that some of pigments are synthetic : [CaCuSi4O10] (egyptian blue) for the blue one, [CuSiO,, nH2O] formula closely related to chrysocolla which looks like molten glass for the green one, clay mixed with hematite (composition closely related to an ochre) for the red one. The white pigment is obtained with powered shell. The yellow pigment is an ochre with unidentified cubic cristals containing Fe, S, Si, K, Al. Answering the archaeological problem, this study is dealing with a better knowledge of archaeological materials and ancient technologies., Ce travail est consacré à la caractérisation de pigments picturaux mis au jour en août 1984 par les architectes- archéologues de la Mission permanente du CNRS à Karnak, Egypte. Décrites comme des éléments de la palette d'un peintre, ces matières colorantes comportent des pigments de couleur bleue, rouge, blanche, verte, et jaune. Leur caractérisation a été effectuée en utilisant des méthodes désormais classiques en physique appliquée à l'Archéologie : microscopie à balayage pour l'observation des faciès et des textures, microanalyse X pour l'analyse élémentaire et diffraction X pour 1 analyse cristallographique. Les résultats obtenus indiquent que deux d'entre eux sont des pigments de synthèse : [CaCuS^OjJ (bleu égyptien) pour le bleu, [CuSiO3, nH2O] formule proche de la chrysocolle qui se présente sous forme d'une pâte de verre pour le vert. Le rouge est un mélange d'argile et d'hématite pure (composition proche de celle d'une ocre). Le blanc a été obtenu par broyage d'un coquillage. Le jaune est une ocre dans laquelle nous avons décelé des cristaux cubiques dont la nature n'a pas été déterminée mais qui contiennent du fer, du soufre, du silicium, du potassium, et de l'aluminium. Cette étude, qui répond aux interrogations des archéologues, s'inscrit dans une perspective de renforcement et d'affinement des connaissances sur les matériaux archéologiques et les technologies anciennes., Rouchon Olivier, Fabre Jane, Etcheverry Marie-Pierre, Schvoerer Max. Pigments d'Egypte, étude physique de matières colorantes bleue, rouge, blanche, verte et jaune, provenant de Karnak. In: Revue d'Archéométrie, n°14, 1990. pp. 87-97.

Optical and EPR measurements are carried out on shattuckite, a copper bearing silicate. The EPR spectrum observed at 120 K reveales hyperfine structure for parallel and perpendicular components. The measured values are g ‖ = 2.402, g ⊥ = 2.038, A ‖ = 112 × 10 -4 cm -1 and A ⊥ = 49.5 × 10 -4 cm -1 and they indicate a tetragonal distortion for the Cu 2+ ion . Further, the constants P and K are evaluated and found to be 0.014 cm -1 and 0.0112 respectively. The bands observed at 8160, 13330 and 16125 cm -1 are assigned to the electronic states of Cu 2+ , in a crystal field subjected to tetragonal (C 4V ) distortion. The crystal field parameters evaluated are Dq = -1333, Ds = -1565 and Dt = -380 cm -1 . Correlating the EPR and optical data, the orbital reduction factors are calculated as k ‖ = 0.89 and k ⊥ = 0.59. It is confirmed from EPR and optical studies that the Cu 2+ ion in shattuckite is sited in an elongated octahedron. Similar studies are carried out for plancheite. The observed optical absorption spectrum of plancheite is attributed to Cu 2+ sited in an elongated octahedron and tetragonal field parameters are evaluated.

Timna' chrysocolla was divided into several types based on two end members differing in water content, specific gravity, CuO:SiO2 ratio and apparently also in their DTA behaviour. The chrysocolla replaces quartz. In places an intergrowth of chrysocolla and wilkeite was observed by electron probe scanning. The X-ray diffraction pattern of chrysocolla is rather poor; however diffraction patterns were obtained after controlled heating (DTA). These indicated the crystallization of tenorite, cuprite, quartz and cristobalite. Dioptase, plancheite and bisbeeite were also identified by X-ray diffraction. Several possibilities of chrysocolla genesis are discussed.

Genesis and evolution of copper silicates in the ore deposit of Mindouli, Congo The weathering processes which affect the sulfide mineralization of Mindouli (Congo) leads to the individualization of various secondary products : carbonates, silicates and oxides. The silicate pangeneses which were recognized consist of dioptase (CuSiO3.H2O), plancheite (Cu7Si8O22(OH)2) and chrysocolla (Cu7Si8O2O(OH)8.8H2O). These different copper silicates can directly result either from the transformation of parent sulfides like chalcocite (Cu2S), or from recrystallizations after the dissolution of the secondary copper minerals (carbonates and silicates), or from the replacement of lead carbonate (PbCO3). In the majority of the studied cases, the transformation is characterized by conservation of original mineral structures so that the chemical composition of secondary cupriferous minerals reflects partly the parent materials from which they derive., Les altérations météoriques qui affectent la minéralisation sulfurée de Mindouli au Congo conduisent à l'individualisation de nombreux produits secondaires : carbonates, silicates et oxydes. Il est mis en évidence différentes générations de silicates de cuivre : dioptase (CuSiO3.H2O), planchéite (Cu7Si8O22(0H)2) et chrysocolle (Cu7Si8O20(OH)8.8H2O). Ces différents silicates de cuivre résultent soit directement de la transformation des sulfures cuprifères parentaux comme la chalcocite (Cu2S), soit de recristallisations à partir de la dissolution des anciens minéraux cuprifères secondaires (malachite, carbonates et silicates de cuivre), soit enfin de pseudomorphoses du carbonate de plomb (cérusite, PbCO3). Dans la majorité des cas analysés, la transformation s'est faite avec conservation de la structure du minéral originel. Aussi la composition chimique des phases secondaires cuprifères reflète-t-elle, en partie, celle du matériau parental., Koud Jean-Mathias. Genèse et évolution des silicates de cuivre dans le gisement de Mindouli au Congo. / Genesis and evolution of copper silicates in the ore deposit of Mindouli, Congo. In: Sciences Géologiques. Bulletin, tome 41, n°3-4, 1988. pp. 279-288.

The orthorhombic crystal structures of shattuckite, Cu(5)( SiO(3))(4)(OH)(2) and planchétite, Cu(8)(Si(4)0(11))(2)(OH)(4) H(2)O, have been solved. Shattuckite contains silicate chains similar to pyroxene in a complex association with copper atoms, while the closely related planchéite contains silicate chains similar to amphibole.