An investigation and evaluation of the redox conditions around an underground rock cavern are important from the viewpoint of the safety assessment of the subsurface geological disposal of radioactive wastes. The in situ redox conditions around a cavern excavated in Neogene pyroclastic rocks were investigated. Rock samples were collected from a tunnel wall crossing the oxidation front, and the properties of pore water seeping into small holes drilled in the tunnel wall were determined. Chemical analysis of the rock samples revealed that pyrite-bearing rocks belowthe oxidation front were oxidized by the dissolved oxygen in the groundwater infiltrating from the surface. The water properties changed with increasing oxidation of the rocks. From the amount of oxygen-consuming components in the rocks, the migration rate of the oxidation front was estimated to be ~0.2 mm/y due to the flowrate of groundwater (0.1 m/y) containing oxygen.

There are many basic copper chlorides and sulphates which occur as minerals but have received little recent crystallographic study. Yet copper is a widely distributed element and many of these minerals are the products of corrosion and weathering of bopper and copper ores.

In 1948 we were able to confirm the earlier goniometric work of G. F. Herbert Smith (1906) that paratacamite and atacamite are not identical species (Max H. Hey, 1950) and showed that the two minerals give different X-ray powder patterns. This result was further extended by Clifford Frondel (1950) to a single 'crystal and thermal study of paratacamite, in the course of which he measured the rhombohedral unit-cell dimensions and showed that this mineral can be artificially produced by various methods as well as by the action of salt-water on copper.

Aconspicuous feature of all published diagrams, showing the results of the determination of a number of plagioclase felspars by the Fedorov method, is the pronounced scattering of the poles. They lie not only on the curves of the determinative stereogram, but on either side of them, and, in fact, occupy a belt, varying in different instances, and in different positions along the length of the same curve, from 3 to 8 mm. in width. These belts usually contain, but are not symmetrically disposed to, the curves.

Mineralogic data on a chrome garnet, a spessartine, and a spandite from India are presented. The chrome garnet, named hanléite by Fermor, carries 89·7 % uvarovite, and is not a distinct mineral. The end-member compositions of the manganese garnets, recast from their chemical analyses, lend support to the existence of calderite and blythite as garnet end-members.

Scarcely in any case has the meteoric origin of any iron been more doubtful than that of the Greenland masses found by Professor Nordenskjòld in 1870, for although they contain about 2 per cent. of nickel, and, when etched, show the Widmanstätt’s figures, the fact that iron is imbedded in the basalt, on which the so-called meteorites were lying, bespeaks that the loose masses of iron originally belonged to the basalt.

“The Blue Rocks” (Danish, Blaafjeld, Greenland, Ovifak), on the southern coast of Disko, where the iron was found, are about 1800 feet high; the foot up to 600 or 700 feet is covered by loose stones forming a slant of 30 or 40° above which, in the almost perpendicular rock, 13 or 14 horizontal seams of trap are seen.

Boscardinite, ideally TlPb4(Sb7As2)∑9S18, has been described recently as a new homeotypic derivative of baumhauerite, found at Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. New findings of boscardinite in different mineral associations of this deposit have allowed the collection of new crystal-chemical data. Electron-microprobe analysis of the crystal used for the single-crystal X-ray diffraction study gave (in wt.%): Ag 1.81(5), Tl 12.60(21), Pb 17.99(12), Hg 0.14(5), As 9.36(12), Sb 33.60(27), S 23.41(30),Cl 0.06(1), total 98.97(100). On the basis of ∑Me = 14 apfu, it corresponds to Ag0.42Tl1.52Pb2.14Hg0.02 (Sb6.82As3.08)∑9.90S18.04Cl0.04. With respect to the type specimen, these new findings are characterized by a strong Pb depletion, coupled with higher Tl contents, and a significant As enrichment. The single-crystal X-ray diffraction study of this (Tl,As)-enriched boscardinite confirms the structural features described for the type sample. The unit-cell parameters are a = 8.1017(4), b = 8.6597(4), c = 22.5574(10) Å, α = 90.666(2), β = 97.242(2), γ = 90.850(2)°, V = 1569.63(12) Å3, space group P̄1. The crystal structure was refined down to R1 = 0.0285 on the basis of 6582 reflections with Fo > 4σ(Fo). Arsenic is dominant in three MeS3 sites, compared to one in type boscardinite. The main As-enrichment is observed in the sartorite-type sub-layer. Owing to this chemical peculiarity, (Tl, As)-rich boscardinite shows alternation, along b, of Sb-rich sites and As-rich sites; this feature represents the main factor controlling the 8 Å superstructure. The chemical variability of boscardinite is discussed; the Ag increase observed here gets closer to stoichiometric AgTl3Pb4(Sb14As6)∑20S36 (Z = 1), against possible extension up to AgTl2Pb6(Sb15As4)∑19S36 for type boscardinite.

Ianbruceite, ideally [Zn2(OH)(H2O)(AsO4)](H2O)2, is a new supergene mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia. It occurs as thin platy crystals up to 80 μm long and a few μm thick, which form flattened aggregates up to 0.10 mm across, and ellipsoidal aggregates up to 0.5 mm across. It is associated with coarse white leiteite, dark blue köttigite, minor legrandite and adamite. Ianbruceite is sky blue to very pale blue with a white streak and a vitreous lustre; it does not fluoresce under ultraviolet light. It has perfect cleavage parallel to (100), is flexible, and deforms plastically. The Mohs hardness is 1 and the calculated density is 3.197 g cm-3. The refractive indices are α = 1.601, β = 1.660, γ = 1.662, all ±0.002; 2Vobs = 18(2)°, 2Vcalc = 20°, and the dispersion is r < v, weak. Ianbruceite is monoclinic, space group P21/c, a = 11.793(2), b = 9.1138(14), c = 6.8265(10) Å, β = 103.859(9)°, V = 712.3(3) Å3, Z = 4, a:b:c = 1.2940:1:0.7490. The seven strongest lines in the X-ray powder diffraction pattern [d(Å), I, (hkl)] are as follows: 11.29, 100, (100); 2.922, 17, (130); 3.143, 15, (202); 3.744, 11, (300); 2.655, 9, (230); 1.598, 8, (152); 2.252, 7, (222). Chemical analysis by electron microprobe gave As2O5 36.27, As2O3 1.26, Al2O3 0.37, ZnO 49.72, MnO 0.32, FeO 0.71, K2O 0.25, H2Ocalc 19.89, sum 108.79 wt.%; the very high oxide sum is due to the fact that the calculated H2O content is determined from crystal-structure analysis, but H2O is lost under vacuum in the electron microprobe.

The crystal structure of ianbruceite was solved by direct methods and refined to an R1 index of 8.6%. The As is tetrahedrally coordinated by four O anions with a mean As O distance of 1.687 Å. Zigzag [[5]Zn[6]Znϕ7] chains extend in the c direction and are linked in the b direction by sharing corners with (AsO4) tetrahedra to form slabs with a composition [Zn2(OH)(H2O)(AsO4)]. The space between these slabs is filled with disordered (H2O) groups and minor lone-pair stereoactive As3+. The ideal formula derived from chemical analysis and crystal-structure solution and refinement is [Zn2(OH)(H2O)(AsO4)](H2O)2.

Plagioclase crystal fragments and a block of anorthosite occur in small basaltic dykes on the Jos Plateau. The anorthosite is unusual, for the feldspar is labradoritic, but the interstitial mineralogy is granitic rather than basic, displaying granophyric intergrowths in places. The anorthosite is probably not an intermediate stage in fractionation from a basic parent magma towards granite, since over 95 % of this large province is granitic and the volume of basic magma required would be prohibitively large. Nor did it develop as an intermediate stage in fractionation from a salic parent magma, e.g. syenite, because the plagioclase is too calcic to have crystallized from a syenitic melt. Basic to intermediate dykes are numerous though volumetrically insignificant in the Younger Granite province. The anorthosite may be related to the evolution of small volumes of basaltic magma, which had little to do with Younger Granite magmatism.

The widespread ferristilpnomelane in Dalradian metabasites of the south-west Scottish Highlands has usually formed by secondary oxidation of primary ferrostilpnomelane, probably during weathering. Ferrostilpnomelane oxidizes readily in polished thin sections open to the atmosphere over a period of months, and microprobe examination of the resulting ferristilpnomelane suggests a change in the role of potassium in the structure during oxidation.

Small domestic cooking furnaces are widely used in China. These cooking furnaces release SO2 gas and dust into the atmosphere and cause serious air pollution. Experiments were conducted to investigate the effects of vermiculite, limestone or CaCO3, and combustion temperature and time on desulphurization and dust removal during briquette combustion in small domestic cooking furnaces. Additives used in the coal are vermiculite, CaCO3 and bentonite. Vermiculite is used for its expansion property to improve the contact between CaCO3 and SO2 and to convey O2 into the interior of briquette; CaCO3 is used as a chemical reactant to react with SO2 to form CaSO4; and bentonite is used to develop briquette strength. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside the briquette, and thus brings enough oxygen for combustion and sulphation reaction. Effective combustion of the original carbon reduces amounts of dust in the fly ash. X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive X-ray analysis show that S exists in the ash only as anhydrite CaSO4, a product of SO2 reacting with CaCO3 and O2. The formation of CaSO4 effectively reduces or eliminates SO2 emission from coal combustion. The major factors controlling S retention are vermiculite, CaCO3 and combustion temperature. The S retention ratio increases with increasing vermiculite amount at 950°C. The S retention ratio also increases with increasing Ca/S molar ratio, and the best Ca/S ratio is 2-3 for most combustion. With 12 g of the original coal, 1 to 2 g of vermiculite, a molar Ca/S ratio of 2.55 by adding CaCO3, and some bentonite, a S retention ratio >65% can be readily achieved. The highest S retention ratio of 97.9% is achieved at 950°C with addition of 2 g of vermiculite, a Ca/S ratio of 2.55 and bentonite.

The Eonyang amethyst deposit is thought to be spatially and temporally associated with the biotite granite of the Cretaceous Kyongsang Basin, South Korea. The euhedral quartz crystals in cavities in the aplite which intrudes biotite granite are colour-zoned from white at the base to amethystine at the top. Fluid inclusions from rock-forming quartz in granitic rocks and euhedral quartz crystals in cavities were examined. Three types of primary inclusions were observed and three isochores for inclusions representing each type are constructed to constrain the trapping conditions and fluid evolution involved during the formation of the amethyst. The intersection of the isochore representing the early fluid inclusions with solidus temperature of the host granite indicates initial quartz formation at ~600°C and 1.0–1.5 kbar. Intermediate quartz formation, associated with the high-salinity inclusions, occurred at somewhat lower temperatures (400°C) and pressures of ~1 kbar. The amethystine quartz formed from H2O–CO2–NaCl fluids at temperatures between 280 and 400°C, and pressures of ~1 kbar. Based on the texture and mineralogy of host minerals and on the fluid inclusion characteristics, the euhedral quartz began growing at near solidus conditions of the granite and the pressure did not vary significantly until the end of crystallization of amethystine quartz crystals in cavities. Early quartz in cavities formed from moderately saline fluids that either exsolved from or were in equilibrium with the granite, whereas the amethystine quartz apparently grew from fluids of at least partial sedimentary origin. The granite crystallized at considerable depth under relatively low water pressures probably in the root zones of porphyry-type systems. Hydrothermal activities, fluid compositions and erosion factors combined to provide favourable conditions for the formation of the Eonyang amethyst deposit and its presence near the Earth's surface today.

This paper hypothesizes that arsenic in drinking water indirectly contributes to Buruli ulcer (BU), a skin disease caused by Mycobacterium ulcerans (MU) infection. Samples of groundwater and surface water used as drinking water by the population in Ghana's Amansie West district (part of which has a high prevalence of BU), were collected near rural settlements and analysed for arsenic. Arsenic concentration levels per settlement were compared with BU prevalence. A positive exposure-response relationship was obtained between arsenic in surface water and BU (r2 = 0.82). However, there is no significant exposure-response relation between groundwater and BU.

The equation of state of synthetic deuterated burtite, CaSn(OD)6, has been determined to 7.25 GPa at 298 K by synchrotron X-ray powder diffraction. Fitting to a third-order Birch-Murnaghan equation of state gives K0 = 44.7(9) GPa and K0′ = 5.3(4). A second-order fit gives K0 = 47.4(4) GPa. Within experimental error the two fits are indistinguishable over the pressure range studied. The decrease in the a parameter with pressure is smooth and no phase transitions were observed. Burtite is much more compressible (by a factor of three or four) than CaSnO3 and CdSnO3 perovskites, indicating that the absence of a cavity cation has a major effect upon the compressibility of the octahedral framework. Burtite is also markedly more compressible than the closely-related mineral stottite FeGe(OH)6 (K0 = 78 GPa). Their different compressibilities correlate with the relative compressibilities of stannate and germanate perovskites. Although different octahedral compressions are likely to be the primary reason for the different compressibilities of burtite and stottite, we also consider the possible secondary role of hydrogen-bonding topology in affecting the compressibilities of protonated octahedral frameworks. Burtite and stottite have different hydrogen-bonding topologies due to their different octahedral-tilt system. Burtite, space group Pn and tilt system a+a+a+, has a hydrogen-bonded network of linked four-membered rings of O-H…O linkages, whereas stottite, space group P42/n and tilt system a+a+c−, has <100> O-H…O crankshafts and isolated four-membered rings. These different hydrogen-bonded configurations lead to different bracing of the empty cavity sites by the O-H…O linkages and very different hydrogen-bonding connectivities in these two minerals that may also enhance the difference between their compressibilities.

The crystal structure of khinite, Pb2+Cu2+3Te6+O6(OH)2, orthorhombic, a = 5.7491(10), b = 10.0176(14), c = 24.022(3) Å, V = 1383.6(4) Å3, space group Fdd2, Z = 8, Dcalc = 6.29 g/cm3, from the Empire mine, Tombstone, Arizona, USA, has been solved by direct methods and refined to R1 = 3.2% on the basis of 636 unique observed reflections. There is one distinct Te site occupied by Te and coordinated by six O atoms in an octahedral arrangement with a <Te–O> distance of 1.962 Å. typical of Te6+. There are three octahedrally-coordinated Cu sites, each of which is occupied by Cu2+ with <Cu–O> distances of 2.132, 2.151 and 2.308 Å, respectively. Each Cu octahedron shows four short meridional bonds (~1.95 Å) and two long apical bonds (2.46–2.99 Å) characteristic of Jahn-Teller-distorted Cu2+ octahedra. There is one distinct Pb site occupied by Pb and coordinated by six O atoms and two (OH) groups with a <Pb–O, OH> distance of 2.690 Å. TeF6 and CuΦ6 octahedra share edges and corners to form an [MΦ2] (where Φ = O, OH) layer of composition [TeCu3Φ8]. These layers stack along the c axis at 6 A intervals with Pb atoms between the layers. Identical layers occur in the structure of parakhinite, Pb2+Cu2+Te6+O6(OH)2, hexagonal, a = 5.765(2), c = 18.001(9) Å, V =518.0(4) Å3, space group P32, Z = 3, Dcalc = 6.30 g/cm3. It is only the relative stacking of the TeCu3Φ8 layers in the c direction that distinguishes the two structures, and hence khinite and parakhinite are polytypes.

The crystal structure of balićžunićite, Bi2O(SO4)2, a new mineral species from the La Fossa crater of Vulcano (Aeolian Islands, Italy), was solved from single-crystal X-ray diffraction data and refined to R = 0.0507. The structure is triclinic, space group P1, with a = 6.7386(3), b = 11.1844(5), c = 14.1754(7) Å, α = 80.082(2), β = 88.462(2)°, γ = 89.517(2)°, V = 1052.01(8) Å3 and Z = 6. The crystal structure consists of six independent Bi sites, six S sites and 27 O sites of which three are oxo oxygen atoms not bonded to sulfur. Bismuth and S atoms are arranged close to a eutectic pattern parallel to the (100) plane. The planes are stacked atom on atom such that Bi always overlays S and vice versa. This structural feature is shared with the known structure of the high-temperature polymorph of the same compound, stable at T >535°C. However, the sequences of Bi and S atoms in the two structures are different and so are the arrangements of oxygen atoms. Characteristic building blocks in the structure of balićžunićite are clusters of five Bi atoms which form nearly planar trapezoidal Bi5 groups with oxo oxygens located in the centres of the three Bi3 triangles, which form the trapezoids. The trapezoidal Bi5O39+ ions are joined along [100] with SO42– groups by means of strong bismuth-sulfate oxygen bonds, forming infinite [100] rods with composition Bi5O3(SO4)5–. One sixth of the Bi atoms do not participate in trapezoids, but form, with additional SO42– groups, rows of composition BiSO4+, also parallel to [100]. [Bi5O3(SO4)5–] rods form infinite layers parallel to (010) with [BiSO4+] rows located on the irregular surface of contact between adjacent layers. Bi atoms occur in four different coordination types, all showing the stereochemical influence of the Bi3+ lone electron pair. In this respect the crystal structure of balićžunićite shows greater variability than its high-temperature polymorph which has only two types of the Bi coordination spheres present in balićžunićite.

The crystal structure of stephanite fromthe type locality, Freiberg District, Saxony, Germany, was refined in the space group Cmc21, up to a final R index of 0.0427. Unit-cell parameters are: a 7.8329(6) Å, b 12.458(1) Å, c 8.5272(7) Å, V 832.1(1) Å3; Z = 4. The previously reported structural model is confirmed, but a higher-precision refinement was achieved herein by the introduction of thirdorder non-harmonic Gram-Charlier tensors for one Ag atom. In the structure of stephanite, Sb forms isolated SbS3 pyramids, which typically occur in sulphosalts, and Ag occupies sites with coordination ranging fromtriangular to almost tetrahedral. Both the Sb–S and Ag–S bond distances closely match the values commonly observed in the structures of other Ag sulphosalts and sulphides.

The use of non-harmonic parameters for Ag allowed a better description of the electron density related to Ag, which is usually difficult to refine in good ionic conductors. A careful analysis of the energy barriers between the Ag sites defines preferred ion-diffusion pathways within the crystal structure of stephanite. The diffusion of Ag ions occurs preferentially along the sites Ag1 and Ag2, giving rise to two-dimensional nets of Ag atoms in which the ion conduction probably takes place.

Fitted Mössbauer spectra are presented for a set of anthophyllites and gedrites. Despite their complexity it is possible to obtain fits for gedrite spectra and the Mössbauer parameters are consistent with results for anthophyllites from this and previous studies. At least three doublets are required to fit the Fe2+ absorption in gedrites; there is no single model at present to explain the behaviour of the spectra. Fe3+ absorption is also resolved.

Chromiferous spinel and chlorite are associated and sometimes intergrown in serpentinized peridotites at Chimwadzulu Hill. The peridotites probably crystallized from a melt under the conditions of the spinel-lherzolite facies (O'Hara, 1967) in which the stable aluminous phase is spinel. The spinel that formed was probably a chromite with some Al2O3 and MgO. At lower temperatures aluminous spinel is unstable in the presence of olivine and orthopyroxene, chlorite being the stable aluminous mineral. It is thought that the chlorite crystallized under the conditions of medium-grade metamorphism that prevailed when the rocks were emplaced, and at the same time the spinel recrystallized, depleted in Al2O3 and MgO and correspondingly enriched in FeO, Fe2O3, and Cr2O3, giving rise to the observed chromite-chlorite association.