Phengite and chlorite have undergone decomposition during pyrometamorphism caused by the intrusion of a dolerite feeder pipe into Dalradian greenschists in Argyllshire, Scotland. All reaction products are extremely fine grained. Transmission electron microscopy has revealed that phengite pseudomorphs consist of biotite, spinel, mullite, sanidine and phengite, and that chlorite pseudomorphs consist of combinations of chlorite, spinel, orthopyroxene, magnetite, cordierite and biotite. Although the reactions were short-lived and did not go to completion, microprobe analysis and phase diagram analysis have revealed that there has been significant chemical interaction between the phyllosilicates and the surrounding rock. Numerous orientation relationships exist between the original minerals and their reaction products; the close-packed planes in the precursor phyllosilicates were inherited by their reaction products.

Electron probe microanalyses carried out on thirty areas of lithiophorite (Al,Li)MnO2(OH)2 from five Australian localities indicate wide variations in its Ni, Co, Cu, and Zn content. The concentration of these elements varies inversely with the alumina content, though there is a marked change in their concentration at 18% alumina, suggesting the existence of two varieties of lithiophorite with differing concentration of transition elements. EPMA line scans also indicate definite changes in Co content in lithiophorite grains less than 0.2 mm in dimension. The variations in alumina and transition elements may be explained if lithiophorite is considered to be an irregular mixed-layer-lattice intergrowth of pure lithiophorite with members of the recently discovered asbolane-type minerals.

Six specimens of talc studied by the electron microscope lattice-imaging and diffraction techniques were found to have the triclinic one-layer (1 Tr) structure. Since no evidence of a monoclinic two-layered structure was found in any specimen it is concluded that the 1 Tr structure is the common one for talc, and it may, moreover, be the only one. Extremely fine polysynthetic twinning and single intrinsic stacking faults were found in talc.

Rumseyite, ideally [Pb2OF]Cl, is a new mineral species which is associated with calcite, cerussite, diaboleite, hydrocerussite and undifferentiated Mn oxides in a small cavity in 'hydrocerussite' from a manganese pod at Merehead quarry, Somerset, England. Rumseyite is tetragonal, I4/mmm, a = 4.065(1), c = 12.631(7) Å, V = 208.7(1) Å3, Z = 2. The mineral is translucent pale orange-brown with a white streak and vitreous lustre. It is brittle with perfect {100} cleavage; Dcalc = 7.71 g cm–3 (for the ideal formula, [Pb2OF]Cl). The mean refractive index in air at 589 nm is 2.15. The six strongest reflections in the X-ray powder-diffraction pattern [dmeas in Å, (Irel), (hkl)] are as follows: 2.923(100)(013), 2.875(68)(110), 3.848(41)(011), 6.306(17)(002), 1.680(14)(123), 2.110(12)(006). The crystal structure of rumseyite is based on alternating [OFPb2] and Cl layers. Rumseyite is related to other layered Pb oxyhalides. Fluorine and oxygen are statistically disordered over one crystallographic site. Rumseyite is named in honour of Michael Scott (Mike) Rumsey (1980– ), Curator and Collections Manager at the NHM (London), who discovered the mineral. The mineral and name have been approved by the IMA Commission on New Mineral Names and Classification (IMA 2011-091). The holotype specimen is in the collections of the Natural History Museum, London (specimen number BM1970,110).

Small deviations from higher symmetry can be established by single-crystal diffraction methods by (1) measuring the metric of the unit cell with high, non-routine precision; (2) measuring a full reflection sphere of diffraction data and testing it for the presence or absence of symmetry elements in the dataset; (3) refining the structure in both the higher and the lower symmetry and comparing the results; (4) checking the refined crystal structures for the presence or absence of hidden symmetry elements. By these criteria it is not established that the v{120} growth sector of yugawaralite really has triclinic symmetry (Tanaka et al., 2002). On the contrary, the refined metrical parameters and the atomic positions conform to monoclinic symmetry within the margins of experimental error.

Goldmanite, the vanadium analogue of grossular and andradite, was found as subrounded green porphyroblasts ranging from 0.1 to 1.7 mm in size in the carbonaceous black slates from the Deokpyeong area of the Ogcheon belt in Korea. A radiating aggregate of slightly curved blades of goldmanite crystals displays birefringence and replaces the fine-grained black matrix. The V2O3 content ranges from 21.9 to 26.6 wt.% (24.0 wt.% average), higher than previously reported values. The calculated mole % of the goldmanite end-member ranges from 72 to 91. Its cell dimension was calculated to be 12.04 Å from X-ray diffraction. The black slate in the Deokpyeong area is the richest known accessible source of relatively pure goldmanite.

Conversion of randomly ordered illite-smectite to ordered illite-smectite in the Upper Jurassic Kimmeridge Clay Formation from the North Sea has been recorded in the literature as occurring within the ‘oil window’ and has been suggested as an indicator of oil source rock maturity. Studies of authigenic clay minerals in the fine fraction (>0.5 µm) of the Kimmeridge Clay Formation mudstones from fourteen locations along the UK onshore outcrop between Dorset and North Yorkshire show that they comprise mainly ordered illite-smectites. The onshore Kimmeridge Clay section is organically immature, suggesting that the illite-smectite ordering reaction cannot be extrapolated between basins as an inorganic indicator of ‘oil window’ levels of maturity. These results also have important implications in source rock hydrocarbon expulsion and migration models which involve shale dewatering as a flushing agent. However, dewatering of shales may aid migration as it could cause fracturing of the shale bands separating the organic-rich layers within the source rock, prior to hydrocarbon generation.

Active geothermal systems in fluvial-deltaic sediment of the Salton Trough typically develop a thick, carbonate-cemented sandstone caprock which shows a regular progression of carbonate minerals, mineral reactions, rock-fluid mass transfer, and physical properties on increasing temperature. The Sinclair 3 well contains calcian ankerite at < 175 °C, ankerite from 175 to 195 °C, calcite+minor dolomite from 195 to about 250°C, and calcite at higher temperatures. The carbonate content of sandstone decreases on increasing temperature from > 45% at < 140 °C to about 10% at > 250 °C, The most abrupt decrease occurs in the 140 to 170°C range where significant compaction of sandstone occurs as carbonate is reduced to < 25%, and kaolinite reacts to form chlorite. The overall result is the loss of significant Ca, Fe, Mg, and CO2 from sandstone to the fluid phase on increasing temperature. Reaction ofcalcian ankerite to ankerite near 175 °C, and of ankerite to calcite and minor dolomite in the 195 to 245°C range, takes place on a constant carbonate-volume basis by direct replacement of one carbonate by another. The latter reaction produces significant chlorite, with Al derived from solution of detrital feldspar and from the smectite-to-illite transformation. The equilibrium coexistence of calcite with dolomite and ankerite near 200 °C has allowed construction of an isothermal section in the Ca-Mg-(Fe+Mn) carbonate phase diagram and provided a low-temperature constraint on the calcite limb of the calcite-dolomite solvus.

Arsenic is a very common by-product of the processing of Cu, Au and polymetallic ores worldwide, where the ore is roasted (calcined) to remove volatile elements. In southwest England, a diverse range of As-mineral species occur as efflorescent secondary mineral growths on historic calciner buildings. Gypsum occurs as abundant dendritic growths comprising either interlocking blades or tabular crystals. Ca-arsenate minerals are locally very abundant as white colloform masses. Positively identified Ca arsenates include pharmacolite, weilite and haidingerite. Other secondary minerals include arsenolite, scorodite, bukovskyite and an As-bearing potassium alum, together with a wide variety of unidentified minerals, including an Al-As-S phase and As-rich F-bearing phases. Gypsum contains As concentrations up to ~7 wt.%. Efflorescent growth at sites exposed to the prevailing weather systems is less abundant than at sheltered sites. This is interpreted as being due to ‘pressure washing’ of exposed sites by driving rain. Successive concentric growths of gypsum and Ca arsenate on masonry are interpreted as being the result of seasonal crystallization.

Understanding both current and historicalmining and mineralprocessing methods is criticalin the evaluation of the potential impact on the modern environment. In particular, due to the abundance of As-bearing minerals in a wide range of ore types, many buildings worldwide are potentially significantly contaminated with As even though few are directly related to As production or handling. Characterizing the secondary As mineralspecies present at mine and mineralprocessing sites is critical in understanding the potentialheal th risk these sites might pose.

The a-, σ- and π-spectra of quartz in the IR regions were measured under FTIR spectroscopy, and overtone and combination modes perpendicular to the c-axis of quartz were confirmed to be electric vector active by the coincidence of the a-spectrum with the σ-spectrum among the three kinds of spectra. Absorption coefficients of overtone and combination modes intrinsic to the a- σ-, and п-spectra of quartz were measured. The thickness of quartz thin sections can be determined by applying the absorption coefficients obtained from the α- and σ-spectra to the polarized IR absorption spectra measured under E ⊥ the c-axis.

Of the metals in the series Sc, V, Cr, Mn, Fe, and Ga pyroxenes of the type LiM3+Si2O6 were obtained only from Sc, V, Cr, and Fe in dry synthesis experiments near 1000 °C. Ga and A1 gave keatite derivatives (so-called ‘β-spodumenes’) by dry heating; α-Ga-eucryptite was obtained from Ga hydrothermally at pressures between 4·5 and 6·5 kb. Mn gave Mn2O3. The lattice parameters of the pyroxenes vary irregularly with atomic number. This variation and the failure to produce a Mn3+-pyroxene can be explained by the crystal-field theory. At high temperatures A1 and Ga are too small to stabilize a silicate pyroxene phase even at moderately high pressures and form less dense tectosilicates. The octahedral stabilization energy for Cr3+ ensures that Cr, which has the same size as Ga, forms a pyroxene.