Sedimentary basins developed along the European margin during the earliest, Permian, stage of proto-Atlantic rifting, during a phase of high heat flow. The proximity of some basins to Caledonian thrusts has implied that rifts locally utilized the basement fabric. New mineralogical and palaeomagnetic data show that thrust planes in the Moine Thrust Zone channelled a pulse of hot fluid in Permian time. The fluids precipitated kaolin in fractures in the thrust zone, and with decreasing intensity away from the zone. The high-temperature polytype dickite is largely confined to major thrust planes. Stable H and O isotope analyses indicate that the parent fluid included meteoric water involved in a hydrothermal system. Coeval hydrothermal hematite has a chemical remanence that dates the fluid pulse as Permian. This is direct evidence for post-orogenic activity in the thrust zone, in which the thrusts vented excess heat during regional crustal extension. The example from the European margin exemplifies the importance of deep-seated structures in the release of heat, and the value of kaolinite polytype mapping as a tool to record anomalous palaeo-heat flow.

We report micro-Raman spectroscopic studies of FeS2 pyrite in the diamond-anvil cell under hydrostatic and non-hydrostatic conditions to 55 GPa at room temperature. Four out of five Ramanactive modes are resolved with helium as a pressure-transmitting medium to highest pressures. The fifth mode, Tg(2) [377 cm-1], is weak and unresolved lying ∼2 cm-1 from the intense Ag mode [379 cm-1] at 1 bar. We observe an increase in the separation of the Eg [344 cm-1] and Tg(1) [350 cm-1] modes under compression. All observed frequencies increase continuously with increasing pressure showing no evidence for a structural phase transition in accord with both X-ray diffraction and shock-wave studies. The Ag and Tg(1) modes gain significantly in intensity relative to the Eg mode with increasing pressure probably resulting from Raman resonance effects. The Tg(3) mode [430 cm-1] broadens unusually compared to the other pyrite modes with pressure. The Raman data are consistent with a contraction of the S-S and Fe-S bonds under pressure. The main effect of non-hydrostatic conditions on the Raman modes is a strong pressure-induced broadening; the pressure-dependence of the frequencies and relative intensities are not affected within the error of the measurements.

Exsolved garnet, sometimes associated with exsolved amphibole and zoisite, is abundant in aluminous clinopyroxene of garnet clinopyroxenite and clinopyroxenite xenoliths in the early Cretaceous dioriticmonzodioritic intrusions from the Xuzhou region, ∼100 km west of the Sulu ultrahigh-pressure (UHP) metamorphic terrane in eastern China. In addition to the mineral exsolutions, intergranular fine-grained garnet, zoisite, titanite, and sometimes amphibole are also present around the primary clinopyroxene grains. Clinopyroxene shows compositional gradients, with decreasing Al and increasing Si and Mg, adjacent to the garnet lamellae and intergranular garnet. In contrast, the exsolved and intergranular garnet is homogeneous in composition and typically more grossular-rich and pyrope- and almandinepoor than the coarse-grained primary garnet. The estimates of P and T for the precursor assemblage and garnet exsolution suggests a decrease of temperature from ∼950—1100ºC down to 620—780°C, and a nearly constant pressure from ∼15—20 kbar to 18 kbar, which are comparable with the metamorphic conditions of the associated eclogites. Therefore, garnet exsolution in garnet clinopyroxenite and clinopyroxenite xenoliths could be caused by high-pressure (HP) metamorphism. SHRIMP zircon U-Pb dating for the associated eclogite and gneiss xenoliths and Sm-Nd whole rock-garnet dating for the same eclogite demonstrate that parts of lower crust on the southeastern margin of the North China craton might be involved in the Triassic HP metamorphism due to the deep subduction of the Yangtze craton.

Raman spectroscopy was assessed for its ability to rapidly identify asbestos phases by submitting the amphiboles anthophyllite, amosite, crocidolite and tremolite to spectroscopic analysis. All the phases were characterized by using XRD, SEM, TEM (CTEM, SAED), AEM and EDS techniques. This study demonstrates that accurate identification of the mineralogical phase can be attained by analysing the position in the Raman spectrum of the bands corresponding to the symmetric stretching modes (vs) and to the antisymmetric stretching modes (vas) of the different Si—O linkages. Raman spectroscopy thus proves to be an effective technique for rapidly distinguishing the different fibrous minerals examined.

Gold-silver vein deposits in the Taebaeksan district, Korea, coexist in time and space with a variety of other deposit types such as skarns, hydrothermal carbonate replacement bodies and Carlin-like deposits and reflect proximity to a magmatic source. The seven gold-silver deposits within the district show common features such as multiple complex veins, an abundance (up to 30% in ore) of base-metal sulphides, a wide range of Ag/Au ratios and the common occurrence of carbonate. Quartz-vein textures indicate open-space-filling at shallow crustal levels. On the basis of Ag/Au ratios of ore, mode of occurrence, and associated mineral assemblages, the seven deposits studied can be classified as follows; Au-dominant type (Group I), Au-Ag type (Group II), Ag-dominant type (Group IIIA) and base-metal and Ag-dominant type (Group IIIB). Group I is characterized by paragenetically early Pb-Zn basemetal sulphides with electrum and late, rare Ag-sulphides and Ag-sulphosalts, whereas Group III contains more Ag-sulphides and/or Ag-sulphosalts. Group II is gold-rich, but transitional to Group III. The Au contents and FeS contents of electrum and sphalerite, respectively, from all of the deposits decreased as mineralization proceeded. Temperature and log fS2 conditions of gold-silver mineralization tend to decrease from Group I and II to Group III deposits (i.e. 340–270°C, –9.3 to –11.8 bar, 320–240°C, –9.5 to –10.3 bar, 250–160°C, –12.5 to –16.9 bar, respectively) as well as from the main to late stages of mineralization in each deposit. The systematic mineralogy and variation of physicochemical conditions in Groups I, II and III are thought to be due to their relative positions with respect to a magma source that is genetically related to a low-to-intermediate-sulphidation porphyry system. Au-rich deposits are proximal to a magmatic source, whereas Ag-rich deposits are more distal.

A Th-rich mineral of the crandallite group has been investigated from the weathering profile of the Schugorsk bauxite deposit, Timan, Russia. It occurs within thin (up to 0.5 mm) organic-rich veinlets together with ‘leucoxene’ in the form of small shapeless grains which vary in size from 1—2 mm to 60—70 mm. Rare grains disseminated among boehmite crystals were also found. Microprobe analyses determined that the ThO2 content can be as high as 18 wt.%. The mineral composition is intermediate between crandallite CaAl3H(PO4)2(OH)6, goyazite SrAl3H(PO4)2(OH)6, Th-crandallite and svanbergite SrAl3PO4SO4(OH)6 in the beudantite group.

Comparatively high contents of Fe and Si and a very high positive Th and Fe content correlation (r = +0.98) suggest that the formula of the hypothetical Th-bearing end-member is ThFe3(PO4,SiO4)2(OH)6 with Th and Si substituting for REE and Prespectively (woodhouseite-type substitution). Another possible substitution is Th4+ + Ca2+ ⇋ 2REE3+ (florencite-type). A deficiency of cations in the X site can be explained by either the presence of carbon, undetectable by microprobe, in the crystal lattice or a lack of X-site cations due to radiation damage induced by Th. Some excess of cations in the B site (Al and Fe3+) can be explained by the presence of very small boehmite and hematite inclusions on the crandallite grain surfaces. Th-rich crandallite may be the result of alteration of an unidentified silicate mineral from the parent rock with a composition close to the simplified formula Fe2+ThSiO4(OH)2.

The structural behaviour of a haüyne with a chemical composition of Na4.35Ca2.28K0.95[Al6Si6O24]- (SO4)2.03, at room pressure and from 33 to 1035°C on heating, was determined by using in situ synchrotron X-ray powder diffraction data (λ = 0.92249(5) Å). The satellite reflections in haüyne are lost at ∼400°C and a true substructure results because of this phase transition. There is a discontinuity in the a unit-cell parameter at ∼585°C. The α parameter increases rapidly and non-linearly to 585°C, but above 585°C, the expansion rate decreases. The percent volume change between 33 and 576°C is 2.0(3)%, and 0.6(3)% between 593 and 1035°C. Between 33 and 1035°C, the Al–O, Si–O and S–O distances are constant. Between 33 and 576°C, the angle of rotation of the AlO4 tetrahedron, jAl, changesfrom 11.5 to 5.8°, while the angle of rotation of the SiO4 tetrahedron, φSi, changesfrom 12.4 to 6.3°. The Al–O–Si bridging angle changesfrom 150.05(2) to 153.08(1)° from 33 to 576°C. Beyond 585°C, φAl and φSi angles remain nearly constant even though the maximum rotation of the tetrahedra is not achieved. Moreover, the Al–O–Si angle continues to increase at a slower rate from 585 to 1035°C by 1.05(2)°. From 33 to ∼585°C, the K atom position migrates at a slower rate than the Na and Ca atoms, and the structure expands at a high rate. Beyond 585°C, all the atomic positions of the interstitial cations (Na+, K+, Ca2+) remain nearly constant and the expansion of the structure is retarded.

The low-temperature heat capacity of zinc chromite (ZnCr2O4) was measured between 6.5 K and 400 K using adiabatic calorimetry, and some thermochemical functions (CP(T), S(T), S°298, H(T)-H(0)) were derived from the results. The standard entropy (S°298 = 128.6±0.3 J mol-1 K-1) for zinc chromite was calculated from the results. Our calorimetric measurements indicate one extremely large anomaly in the heat capacity curve at ∼12.3 K which is related to the cubic-tetragonal transition in ZnCr2O4.

Holotype material and other specimens of ‘elfstorpite’ from the Sjögruvan deposit, Örebro, Sweden have been characterized by powder X-ray diffraction and chemical analysis. The mineral is indistinguishable from allactite, which has priority, and consequently ‘elfstorpite’ should be discredited. The IMA Commission on New Minerals and Mineral Names has approved the proposition.

One in four of the Cu-filled cation sites in clinoatacamite, the monoclinic polymorph of atacamite and botallackite, is angle- rather than Jahn-Teller-distorted. Experiments show that this site alone is susceptible to substitution by a non-Jahn-Teller distorting cation of suitable radius and charge, such as Zn2+, and also Ni2+, Co2+, Fe2+, Cd2+ and Mg2+. The crystal symmetry changes to rhombohedral when ∼⅓ of the Cu in this site is substituted by e.g. Zn, thus giving paratacamite; the Zn is essential for stability and forms, with larger proportions of Zn, a series to the end-member in which the site is fully occupied by Zn. This end-member, rhombohedral stoichiometric Cu3Zn(OH)6Cl2, has been characterized using natural specimens from Chile and Iran and is named herbertsmithite. The other cations mentioned behave similarly, producing stabilized rhombohedral paratacamites and end-members analogous to herbertsmithite, which if found in nature, as the Ni analogue has been, should be named species. Clinoatacamite, paratacamite and herbertsmithite have rather similar X-ray powder diffraction patterns, but are readily distinguished by infrared spectroscopy.

Zn-stabilized paratacamite forms blue-green crystals of rhombohedral habit, with vitreous lustre, e = 1.828-1.830, o = 1.835, uniaxial negative, weakly pleochroic O > E, density: 3.75 g cm-3, Mohs hardness: 3-3½; space group R, a = 13.654(5), c = 14.041(6) Å, Z = 24, with pronounced Rm substructure; six strongest XRD lines 5.452 (100), 2.895 (20), 2.760 (74), 2.262 (52), 1.817 (18), 1.708 (21).

Herbertsmithite forms dark green crystals of rhombohedral habit, with vitreous lustre, e = 1.817, o = 1.825, uniaxial negative, weakly pleochroic O > E, density: 3.95 g cm-3, Mohs hardness: 3-3½;; space group Rm with no superstructure observed, a = 6.834(1), c = 14.075(2) Å, Z = 3; six strongest XRD lines 5.466 (55), 4.702 (14), 2.764 (100), 2.266 (36), 1.820 (13), 1.709 (18).