Silicate minerals show several correlations between structure type and elastic constants. Stiffness coefficients are generally larger in the direction of Si-O bonding. A simple mechanical analogy in which atomic bonds are simulated by springs connected in series and parallel is used to estimate the size and anisotropy of the elastic moduli and their pressure derivatives.

This study is devoted to fractures produced by natural and artificial shock processes in non-porous rocks consisting essentially of quartz and feldspar. Petrological and textural investigations were performed using optical and scanning electron microscopic techniques. A microfracturation index is adapted from Short (1966, 1968a, b) in order to compare the fracture densities in different materials shocked in different ways. In all cases, the density of fractures in quartz and feldspar increases with increasing pressure to about 200 kb. At higher pressure this trend is reversed. Fracturing is more intense in feldspar than in quartz. Plane shock waves produced in laboratory scale experiments induce more fracturing than natural shock waves. However, such an increase is no larger than the scatter among the data and the experimental technique used in the laboratory can be considered realistic in terms of fracturing. Finally the correlation between pressure and fracture density is too poor to be of use for quantitative pressure calibrations of naturally shocked materials.

There is no direct correlation between the density of fractures and the number of planar elements observed. There is a negative correlation between fracturing and formation of diaplectic glass, Diaplectic glasses are remarkably weakly fractured compared with shocked minerals. The abrupt change in the slope of the curve giving the dependency of the density of fractures with pressure corresponds to the pressure at which diaplectic glass is formed. From petrographic considerations it is deduced that fracturing occurs at the end of the shock sequence, on pressure release, while diaplectic glasses are forming or already formed. Hypotheses of mechanical and thermal fracturing are examined; both are plausible, but a thermal origin may be preferred. The mechanism of formation of diaplectic glass is discussed with respect to results and deductions obtained by the study of fracturing. Diaplectic glass could represent a decompressed highdensity glass resulting from a single state transformation of a mineral, at high pressure.

The Loe Shilman carbonatite sheet complex comprises an extensive amphibole sovite which is intruded by minor biotite sovite and amphibole ankeritic carbonatite. The carbonatites have fenitized the country rocks to form a metasomatic zone c. 100 m wide of alternating mafic and felsic mica-bearing banded fenites which grade into slates and phyllites. Phlogopite-rich micas occur nearest to the carbonatite contact. The biotites occur in K-feldspar + albite ± Na-amphibole ± aegirine and ± phengite fenites produced by the intrusion of the early amphibole sovite. Aegirine buffered the iron distribution and the biotites became more magnesian. Veins cross-cutting the fenites consist of biotite and/or Ba-bearing K-feldspar, and are interpreted to result from solutions emanating from the biotite sovite. The ankeritic carbonatite is responsible for the formation ofphlogopite in the fenites in a c. 3 m wide zone adjacent to the carbonatite, and evidently are the result of fenitizing fluids rich in Mg. Chemical equations calculated to balance the reactions interpreted to have taken place in the fenites suggest that about 10% of the Al and Si in the protolith was mobilized and moved towards the carbonatites during fenitization, and that the fenitizing solutions were strongly alkaline and oxidizing.

Redcanyonite (IMA2016-082), (NH4)2Mn[(UO2)4O4(SO4)2](H2O)4, occurs underground in the Blue Lizard mine, Red Canyon, White Canyon district, San Juan County, Utah, USA. It occurs with natrozippeite, brochantite, devilline, posnjakite, johannite, gypsum, bobcookite, pickeringite, pentahydrite and the NH4-analogue of zippeite: ammoniozippeite. Redcanyonite occurs as radial aggregates of red–orange needles and blades individually reaching up to 0.2 mm long, with aggregates measuring up to 1 mm in diameter. Crystals are flattened on {010} and elongated along [100], exhibit perfect cleavage on {010}, and exhibit the forms {010}, {001}, {101} and {10$\bar{1}$}. Twinning is ubiquitous, by 180° rotation on [100]. Redcanyonite is translucent with a pale orange streak, is non-fluorescent, has a Mohs hardness of 2, and has brittle tenacity with uneven fracture. Optically, redcanyonite is biaxial (+), α = 1.725(3), β = 1.755(3), γ = 1.850(5) (white light); 2V (meas.) = 60(2)°, 2V (calc.) = 61.3°; and dispersion is r < v, very strong. Pleochroism is: X = orange, Y = yellow and Z = orange; Y << X < Z. The optical orientation is X = b, Y ≈ c*, Z ≈ a. The empirical formula is (NH4)2.02(Mn0.49Cu0.09Zn0.06)Σ0.64H+0.72[(UO2)4O4(S0.99P0.01O4)2](H2O)4, based on 4 U and 24 O apfu. Redcanyonite is monoclinic, C2/m, a = 8.6572(17), b = 14.155(3), c = 8.8430(19) Å, β = 104.117(18)°, V = 1050.9(4) Å3 and Z = 2. The structure was refined to R1 = 0.0382 for 1079 reflections with Iobs > 3σI. Uranyl oxo-sulfate sheets in redcanyonite adopt the well-known zippeite topology, which consists of zigzag chains of uranyl pentagonal bipyramids linked by sulfate tetrahedra to form sheets. The sheets are linked to each other through bonds to interlayer NH4+ groups and octahedrally coordinated Mn2+, and by hydrogen bonds from H2O groups. Redcanyonite is named for Red Canyon in southeast Utah, USA.

The new alluaudite-group mineral badalovite was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hematite, tenorite, cassiterite, johillerite, nickenichite, calciojohillerite, bradaczekite, metathénardite, aphthitalite, langbeinite, calciolangbeinite, sanidine, fluorophlogopite, fluoborite, tilasite, anhydrite, pseudobrookite, sylvite, halite, lammerite, urusovite, ericlaxmanite, arsmirandite, svabite, krasheninnikovite, euchlorine, wulffite and alumoklyuchevskite. Badalovite forms oblique-angled prismatic crystals up to 1 mm × 1 mm × 5 mm, typically combined in groups or crusts up to several hundred cm2 in area. The mineral is transparent, green, grey, yellow or colourless, with vitreous lustre. It is brittle, the Mohs hardness is 3½. Cleavage was not observed, the fracture is uneven. Dcalc is 4.02 g cm–3. Badalovite is optically biaxial (–), α = 1.753(3), β = 1.757(3), γ = 1.758(3) and 2Vmeas. = 50(10)°. Chemical composition (wt.%, electron-microprobe; holotype) is: Na2O 9.23, K2O 0.19, CaO 2.04, MgO 13.78, MnO 0.31, CuO 0.12, ZnO 0.24, Al2O3 0.06, Fe2O3 12.77, TiO2 0.01, SiO2 0.06, P2O5 0.33, V2O5 0.05, As2O5 61.51, SO3 0.02, total 100.72. The empirical formula based on 12 O apfu is Na1.67Ca0.20K0.02Mg1.92Zn0.02Mn0.02Cu0.01Fe3+0.90Al0.01(As3.01P0.03Si0.01)Σ3.05O12. The simplified formula is Na2Mg2Fe3+(AsO4)3. Badalovite is monoclinic, C2/c, a = 11.9034(3), b = 12.7832(2), c = 6.66340(16) Å, β = 112.523(3)°, V = 936.59(4) Å3 and Z = 4. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 6.41(38)(020), 5.505(20)(200), 3.577(23)($\bar{1}$31), 3.523(25)(310), 3.211(46)($\bar{1}$12), 2.911(28)($\bar{2}$22, $\bar{3}$12), 2.765(100)(240, 400) and 2.618(26)($\bar{1}$32). The crystal structure was solved from single-crystal XRD data with an R1 of = 2.49%. Badalovite is isostructural with other alluaudite-group minerals. Its simplified crystal chemical formula is A(1)NaA(1)’□A(2) □A(2)’NaM(1)MgM(2)(Mg0.5Fe3+0.5)2(AsO4)3 (□ – vacancy) and the end-member formula is NaNaMg(MgFe3+)(AsO4)3. The mineral is named in honour of the outstanding mineralogist and geochemist Stepan Tigranovich Badalov (1919–2014).

The role of the microbial activity on the transport properties of host rocks for geological repositories, particularly in the far-field, is an area of active research. This paper compares results from experiments investigating changes in transport properties caused by microbial activity in sedimentary rocks in Japan (mudstones) and sandstone (UK).

These experiments show that both Pseudomonas denitrificans and Pseudomonas aeruginosa appear to survive and thrive in pressurized flow-through column experiments which utilized host rock materials of relevance to radioactive waste disposal. Indeed, despite there being a difference in the numbers of organisms introduced into both biotic experiments, numbers appear to stabilize at ∼105 ml−1 at their completion. Post experimental imaging has highlighted the distinct differences in biofilm morphology, for the chosen rock types and bacteria, with Pseudomonas aeruginosa derived biofilms completely covering the surface of the sandstone host and Pseudomonas denitrificans forming biofilament structures. Regardless of substrate host or choice of microbe, microbial activity results in measurable changes in permeability. Such activity appears to influence changes in fluid flow and suggests that the transport of radionuclides through the far-field will be complicated by the presence of microbes.

Electron-diffraction photographs of some natural and synthetic mullites and a typical sillimanite have been obtained and are interpreted using diffraction data due to Agrell and Smith. The position and diffuseness of mullite reflections (h0l) with l = ½ have been re-studied. In such reciprocal lattice sections maxima are symmetrically disposed in pairs about the positions of sillimanite reflections with l odd. They lie on a* rows and show different separations in the specimens studied. These diffraction conditions are closely analogous to those observed in the intermediate plagioclases (paired ‘e’ maxima) and in nepheline, and a similar explanation is envisaged in terms of antiphase domain structure. Intimate association of a mullite-type phase and sillimanite is shown to result from the breakdown of muscovite in a thermal metamorphic aureole, and a chemical analysis of a natural Fe,Ti-bearing mullite from a spinel-mullite buchite in the same aureole, is presented.

A new zeolite closely related to phillipsite and gismondine is recorded from thirty localities in the Tertiary basalts of Antrim and eastern Iceland, and the name garronite is proposed. Four chemical analyses indicate a composition of NaCa2·5A16Si10O32.13·5H2O. Garronite differs chemically from phillipsite in having a very low content of potash, and from gismondine in containing less lime, alumina, and water; optically garronite is intermediate between these two zeolites.

The occurrence of brookite aud anatase within the limits of the Dartmoor granite exposure was first indicated by a sample of stream-sand taken two years ago below the bridge at Dartmeet–a locality which is noteworthy for sands rich ill these and other accessory minerals of the Dartmoor granite.

Anatase, either alone or associated with brookite in small amounts, was found in a majority of the sands taken the following year at selected points along (1) the Plym River, between Cadover Bridge and Hatter Tor, (2) the East Dart and the West Dart, upstream from Dartmeet, (3) the West Webburn, upstream from Ponsworthy, (4) the East Webburn, upstream from Lizwell Meet, and (5) minor streams in the Hamel Down-Bonehill Down area. Rutile proved to be a rare mineral, liable to be overlooked in a residue containing brown cassiterite, from which it cannot readily be distinguished except by microchemical means.

Natural cobalt hydroxide is CoO.OH, not Co(OH)2 as has recently been asserted; for this mineral the name heterogenite has priority. Copper, frequently present, may be in solid solution as (Co,Cu)(O,OH)OH, or may be as finely divided malachite; for cuprian heterogenite, the name schulzenite has priority.

The new pyroxenoid barrydawsonite-(Y) occurs at the Merlot Claim, North Red Wine Pluton, Labrador, Canada (62°32'38.54'' W; 54°08'1.37'' N). The host rock is a metamorphosed eudialyte syenite consisting of eudialyte, potassic arfvedsonite, jadeitic aegirine, nepheline, albite and potassium feldspar with accessory Y-bearing pectolite, britholite and steenstrupine. Barrydawsonite-(Y) crystals commonly have discrete thin rims of Y-bearing pectolite. The average empirical formula (based on nine anions p.f.u.) is Na1.54Ca0.74Mn0.15Fe0.07Y0.38Nd0.01Sm0.01Gd0.02Tb0.01Dy0.04Ho0.01Er0.02Yb0.01Si3.00O9H. The simplified formula is Na1.5Y0.5CaSi3O9H. Barrydawsonite-(Y) is related to pectolite by the substitution ½[NaM3+Ca–2] (M3+ = Y,REE), and is exceptional in being the only member of the pectolite group that has the structure of the monoclinic M2abc polytype. The crystal structure has been determined in monoclinic space group P21/a: a = 15.5026(2), b = 7.0233(1), c = 6.9769(1) Å, β = 95.149(1)°, V = 756.58(2) Å3(Z = 4). Final agreement indices are R1 = 0.038, wR2 = 0.068, Goof = 1.136. The asymmetric unit of barrydawsonite-(Y) has three metal sites: M(1) = Ca, M(2) = Na0.5(Y,REE)0.5, M(3) = Na. M(1) and M(2) are octahedrally-coordinated sites, whereas M(3) is [8]-coordinated as in pectolite and serandite. The structural formula for the empirical composition is M(3)Na1.00M(2)(Na0.50Y0.38REE0.13)Σ=1.01M(1)(Na0.04Ca0.74Mn0.152+Fe0.072+)Σ=1.00Si3O9H. There is excellent agreement between the refined site-scattering values and those calculated based upon the structural formula.

Barrydawsonite-(Y) is biaxial (+) with α = 1.612(1), β = 1.617(1), γ = 1.630(1) (white light) and 2V = 63(1)°. The five strongest peaks in the X-ray powder diffraction pattern are [dobs (Å), Iobs%, (hkl)]: [2.905, 100, (023)], [3.094, 30, (210,211,121,202)], [1.7613, 29, (127,323,040)], [3.272, 27, (202,104)], [1.7016, 27, (140,227,325)].

A garnet-olivine metaperidotite and a garnet-amphibole pyroxenite are described. Chemical analyses are presented for six rocks and optical properties and chemical analyses are tabulated for clinopyroxene, almandine-pyrope garnet, and hastingsitie amphibole from the garnet-amphibole pyroxenite. A possible origin for the garnet peridotite and chemically similar granulite facies ultramafic rocks is suggested. The eclogite facies in South Harris is reinstated in the light of the data presented.

Amongst the specimens recently selected for the British Museum from the collection of South American minerals brought together by the late Theodor Hohmann, are two on which occurs a mineral in thin laminae resembling graphite. From the locality and associations, the mineral was at first presumed to be either franckeite or cylindrite, the two sulphantimonite-sulphostannates of lead from Bolivia, which were described in 1893 by Stelzner and Frenzel respectively. Qualitative analysis, however, soon showed that, although similar to them in physical characters, it differed chemically from both franckeite and cylindrite in containing no antimony, but only lead, tin, and sulphur.

Of the two specimens from the Hohmann collection, one was labelled ‘sulphoselenide of lead from Bolivia,’ and the other ‘selenide of lead from Atacama,’ so that unfortunately the precise locality of the mineral is at present unknown. In all probability both specimens came from the same district in Bolivla, since in appearance they are very similar.

This paper continues the study of the constituent minerals of the Dartmoor granite. The district to which it mainly refers comprises the for-area around Widecombe and a part of the aureole adjoining. No detailed reference will be made at this stage to aureole phenomena. The results to be recorded necessitate a brief description of the two main granite types and of their field relationships. Abundant varieties and modifications of both types occur, but for the Purposes of the present paper they are of subordinate importance.

Most of the for-masses and high-level exposures of granite in the area consist in the main of the type known locally as the ‘giant granite‘ — a very coarse-grained, strongly porphyritic roelc rich in biotite, and consistently garnetiferous; it has an index-figure 1 ranging from 7.5 to 12.

Alamosite was first described by Palachc and Merwin, i who thought it might be isomorphous with wollastolfite. For that reason it has been re-examined, using X-ray methods.

A specimen from the original locality at Alamos, Sonora, Mexico (B.M. 1910,330) was made available through the courtesy of the British Museum (Natural History), and in physical appearance it tallied with the original description. The crystals were aggregates of fibres arranged in bundles which cleaved perfectly perpendicular to the fibre axes. Small tablets could be readily cut out for X-ray analysis. The refractive indices were very high and the dispersion was large. As the axial ratios found by X-ray methods agreed with those given by Palache and Merwin, the latter's chemical analysis and density determination were not repeated.

Pyrite concretions from an arid area of Southern Israel are described. The alteration products include alunite, gypsum, jarosite, baryte, celestine, goethite, hematite, sulphur, and sideronatrite. Sideronatrite is described in detail. The pyrite alteration is considered to be recent and the sideronatrite is preserved owing to climatic aridity. The puzzling appearance of sulphur is tentatively explained by microbiological reduction of the sulphates.

Since its discovery by Tilley in 1930, scawtite has been recognized in several locations in regions of metamorphosed siliceous limestones. Scawtite is believed to be the same as CSH(A) and, as such, has been synthesized sporadically many times during runs in the CaO-SiO2-H2O system where slight contamination from CO2 has occurred. Attempts to synthesize scawtite were successfully carried out at low partial pressures of CO2 in an excess of water. The stability of selected scawtite compositions lies between 140 and 300° C, and above saturated steam pressures is not pressure-dependent, at least up to 50 000 psi. The scawtite facies (2) lies between the tobermorite-calcite facies (3) and the xonotlite-calcite facies (1). A hydration series exists from (1) to (2) to (3).

The thermal disintegration of crocidolite has been investigated with X-ray powder and rotation photographs. Initial disintegration products include monoclinic pyroxene, iron oxide phases, and eristobalite as a pseudomorph of the original fibre bundles but at about 1000° C fusion occurs due to incongruent melting of the pyroxene. The products are strongly oriented along the fibre axis and full orientation relationships have been deduced with the aid of structural models. From these relationships it is suggested that regions of the amphibole structure on (100) are retained in the product phases without change in orientation.

Sectored vesuvianite showing optically triclinic properties was studied by X-ray and P-FTIR analyses, and the origins of the internal optical texture are discussed. A monoclinic refinement (space group P2/n) suggests that site occupancies are slightly different among the Al(2) series, though the OH– dipole is randomly oriented in all sectors. A relationship between the surface and internal texture suggests that these sectoral structures were produced during crystal growth, not by phase transitions.