A new mineral species, staročeskéite, ideally Ag0.70Pb1.60(Bi1.35Sb1.35)Σ2.70S6, has been found at Kutná Hora ore district, Czech Republic. The mineral occurs in the late-stage Bi-mineralization associated with other lillianite homologues (gustavite, terrywallaceite, vikingite, treasurite, eskimoite and Bi-rich andorite-group minerals) and other bismuth sulfosalts (izoklakeite, cosalite and Bi-rich jamesonite) in quartz gangue. The mineral occurs as lath shaped crystals or anhedral grains up to 80 µm × 70 µm, growing together in aggregates up to 200 µm × 150 µm across. Staročeskéite is steel-grey in colour and has a metallic lustre, the calculated density is 6.185 g/cm3. In reflected light staročeskéite is greyish white; bireflectance and pleochroism are weak with greyish tints. Anisotropy is weak to medium with grey to bluish grey rotation tints. Internal reflections were not observed. The empirical formula based on electron probe microanalyses and calculated on 11 apfu is: (Ag0.68Cu0.01)Σ0.69(Pb1.56Fe0.01Cd0.01)Σ1.58(Bi1.32Sb1.37)Σ2.69(S6.04Se0.01)Σ6.05. The ideal formula is Ag0.70Pb1.60(Bi1.35Sb1.35)Σ2.70S6, which requires Ag 7.22, Pb 31.70, Bi 26.97, Sb 15.72 and S 18.39 wt.%, total 100.00 wt.%. Staročeskéite is a member of the lillianite homologous series with N = 4. Unlike gustavite and terrywallaceite, staročeskéite, similarly to lillianite, is orthorhombic, space group Cmcm, with a = 4.2539(8), b = 13.3094(8), c = 19.625(1) Å, V = 1111.1(2) Å3 and Z = 4. The structure of staročeskéite contains four sulfur sites and three metal sites: one pure Pb site and two mixed sites, M1 (0.52Bi + 0.356Ag + 0.124Sb) and M2 (0.601Sb + 0.259Pb + 0.14Bi). The mineral is characterized by the Bi:Sb ratio 1:1 (Bi/(Bi + Sb) = 0.50) and the Ag+ + Bi3+, Sb3+ ↔ 2 Pb2+ substitution (L%) equal to 70%. Thus the mineral lies between two series of the lillianite structures with N = 4, between the lillianite–gustavite series and the andorite series.

At the Morrua pegmatite, Mozambique, alkali feldspar has replaced pollucite under low-temperature (250–150°C) hydrothermal conditions. Fluids invading a fracture system in pollucite formed round granular aggregates of (K-Rb)-feldspar in three stages: (1) a compositionally heterogeneous core of the feldspar cluster (+cookeite ± apatite) with 7–20 mol.% RbAlSi3O8, grading outward into a Rb-dominant feldspar with 66 mol.% RbAlSi3O8 (20 wt.% Rb2O); (2) an intermediate layer of non-porous, inclusion-free, end-member K-feldspar; (3) an outer layer of porous end-member K-feldspar. Feldspars of all three stages seem to be monoclinic and disordered, with metastable sanidine structure. Zoning in K/Rb, preserved on a fine scale, was formed during growth at a temperature too low for subsequent alkali-cation diffusion or (Al,Si)-ordering.

This study presents the first crystal-structure determination of natural MgCO3·5H2O, mineral lansfordite, in comparison with previous structural works performed on synthetic analogues. A new prototype single-crystal X-ray diffractometer allowed us to measure an extremely small crystal (i.e. 0.020 mm × 0.010 mm × 0.005 mm) and refine anisotropically all non-hydrogen atoms in the structure and provide a robust hydrogen-bond arrangement. Our new data confirm that natural lansfordite can be stable for several months at room temperature, in contrast with previous works, which reported that such a mineral could be stable only below 10°C.

Corrosion of steel canisters, disposed of in a repository for high-level waste (HLW), leads to generation of hydrogen gas for a long period after the repository's closure. The accumulation of hydrogen gas may lead to significant desaturation and unacceptable build-up of pressure in the backfilled disposal tunnels if the gas cannot escape through the low-permeability host rock. Consequently, the investigation of gas migration is of high relevance in the assessment of the repository's performance.

In this paper, the results of numerical investigations on gas migration performed using the computer code TOUGH2 (USA) are presented. The objective was to investigate migration of gas generated in a single disposal tunnel of a conceptual geological repository in a clay formation, which was suggested for benchmark studies in the European Commission project FORGE (Fate Of Repository GasEs). The analysis was focused on evaluation of the impact of an initial temperature in the repository and of different tortuosity models on gas migration. It was revealed that gas migration results were dependent on tortuosity model, while temperature variation in the repository had minor impact.

The fluorites of the Transvaal occur in different rock-types, viz in the dolomite of the Transvaal System, in acidic rocks (red granite and granophyre of the Bushveld igneous complex and Rooiberg felsites), and in alkalic rocks. The purpose of this study was to determine:

1. (1) What minor elements are present in selected fluorites.

2. (2) What the effect of these elements is on the respective cube-edges.

3. (3) Whether these elements have any geological significance.

Fluorite displays a wide range of colour; both colourless and distinctly coloured specimens were examined. Differently coloured varieties could in some instances be taken from the same sample. The choice of coloured varieties in the different rock-types was nevertheless limited. Only light-coloured fluorites occur in the dolomite, whereas the alkalic rocks yielded only very dark purple specimens.

The determination of the specific gravity of a solid which is only available in small quantity has always been a difficult problem in cases where the suspension method fails, either because the solid is too dense, or because it dissolves in or reacts with the heavy liquids available. It is hoped that the following method will be found a useful addition to the numerous methods which have been proposed from time to time to meet such cases. References to most of these methods are given at the end of the paper. Neither the new method nor any one of the older ones is universally applicable, and the best method for any particular case will depend on many circumstances.

The third occurrence of stokesite was discovered in a desilicated pegmatite at Věžná, Western Moravia. In this locality, stokesite accompanies columbite, cassiterite, and stibian pyrochlore-microlite, in a miarolitic cavity of albite. The X-ray data and the optical properties of the Věžná stokesite agree well with those observed by previous authors.

The Middle Lias of Rutland, east Leicestershire, and north-west Northamptonshire was described by Judd in 1875 as comprisingan upper ferruginous member—-the Marlstone Rock Bed-—and a lowerargillaceous division of blue clays, often micaceous or sandy, and carryingbands of 'septaria' and of 'ironstone balls'. In the septaria he recordedthe occurrence of 'specular-iron, zinc-blende and pyrites'.

During the six-inch survey of one-inch New Series sheets 157 (Stam-ford) and 171 (Kettering) together with the adjacent parts of sheets 156(Leicester) and 170 (Market Harborough) a considerable area of thelower argillaceous division was mapped.

For several years now it. has been generally appreciated that plagioclase felspar formed at high temperature differs optically from that formed at lower temperatures. Much of the evidence for this has been provided by the Austrian workers, notably Köhler (1-3), Scholler (4), and Tertsch (5-7), who have prepared revised curves to supplement the universal-stage stereograms of Reichert (which are for use with lowtemperature material). There are a number of interesting petrological points which have not yet been fully investigated. Much work has been done on synthetic material, and it is not clear to what extent the hightemperature forms occur naturally. There may be two distinct and separate types of plagioclase structure, or the two forms may grade into one another. It may be possible to explain the optical anomalies as an order-disorder phenomenon; a more disordered state has been 'frozenin' in those felspars which ha~e formed a.t a high temperature and cooled rapidly.

At the suggestion of, and with much assistance from, Dr. L. J. Spencer, Keeper of Minerals in the British Museum, I have examined and, as far as possible, verified and corrected the recorded places of fall of all reported Indian meteorites. The original records were consulted, and as far as possible the places found on the large scale (usually 1 inch = 1 mile) maps in the India Office. This left a residuum regarding which inquiries were made of District Officers in India, to several of whom I am indebted for useful information which has been embodied in the list.

In this list the falls are entered under their original names in alphabetical order by Provinces in British India, but in one list for all the Indian States, and the positions are indicated on the map (plate XII). The correct names of the places of fall are given in each case, in some only the spelling has required correction in accordance with the Government of India standard system, in others the vernacular name has clearly been mistransliterated, and in many cases the name of the district or province has been changed since the fall. Wherever possible the exact date and time of fall, the latitude and longitude of the place thereof, and its distance from some big place or railway station have been given.

From a metallographic study the thermo-mechanical history of Kodaikanal is proposed as a slow structure-forming cool, followed by mechanical damage, then mild reheating, and finally entry to earth.

While engaged last summer in arranging the Carne collection of minerals acquired for the Cambridge Mineralogical Museum in the early part of 1899, my attention was attracted by a single, colourless, transparent crystal, about 10 mm. long, implanted in a shallow cavity on a specimen of crystallised axinite from the St. Just district of Cornwall. In general appearance the crystal resembled somewhat closely one of selenite of the ordinary habit, and indeed was entered as gypsum in the catalogue of the Carne collection.

A new data analysis toolkit which is suitable for the analysis of large-scale, long-term datasets and the phenomenon/anomalies they represent is described. The toolkit aims to expose and quantify scientific information in a number of forms contained within a time-series based dataset in a quantitative and rigorous manner, reducing the subjectivity of observations made, thereby supporting the scientific observer. The features contained within the toolkit include the ability to handle non-uniform datasets, time-series component determination, frequency component determination, feature/event detection and characterization/parameterization of local behaviours. An application is presented of a case study dataset arising from the 'Lasgit' experiment.

Mapping of the distribution of zeolites in the Antrinl basalku has revealed that gmelinite is confined to a narrow zone along the eastern seaboard of Antrim. This zone comprises less than 1% of the area of the basalts, but in it gmelinite is extremely abundant. The gmelinite zone is superimposed upon the lava pile, and the minerals in it are clearly later than the laves; it is in the form of a dome, elongated north-west and traceable for 18 or 24 miles in this direction, and is found in the basal parts of the lava pile, locally reaching a height of some 500 feet in the pile. The zone may be related in its position and origin to the Island-magee fault zone. Gmelinite frequently forms a parallel overgrowth on chabazite. Superimposed upon the southern part of the gmclinite zone is a zone of late chabazite and heulandite containing, inter alia, parallel overgrowths of late chabazite on simple or twinned gmelinite.

The published data on these three minerals, first found in the Laurion lead slags, is well summarized in Hintze (Handb. Min., 1915, vol. 1, pp. 2632-2641). In studying the original papers for the purpose of recalculating the elements of each, LaForge was impressed with their close crystallographic relationship in certain respects and with the curious complexity of the form series of fledlerite, which seemed to call for further observations. Accordingly, crystals of all three minerals from Laurion were studied on the goniometer, specimens loaned by the U.S. National Museum furnishing a welcome supplement to those found in the Harvard Mineralogical Museum. In the following pages the results of these studies will first be presented in brief form. Following this, the conclusion arrived at as to the most appropriate positions of the three minerals to bring out their mutual relationships will be stated.

Three new analyses of kalsilite are given, with optical and X-ray data; two (K/(K + Na) = 0·95. 0·98) are from rocks where it is closely associated with nepheline. An analysis of one of the nephelines is also given (K/(K + Na) = 0·31). The cell dimensions vary appreciably with sodium content, and the composition of kalsilite may be determined from the equation:

100 K/(K + Na) = 100−227·27(Δ 6·264),

where Δ is the difference, in degrees, between the diffraction angles 2ϑ for 102 and 101, using Cu-Kα radiation.

The mass suseeptibility of 23 analysed or partially analysed garnets has been measured by means of a calibrated Franz Isodynamic magnetic separator. Straight lines are fitted to the adjusted data for mass susceptibility and molecular composition. The mass susceptibilities of the theoretical end-members in electromagnetic units × 106 are estimated as: almandine, 68±2 e.m.u.; spessartine, 81±3 e.m.u.; and andradite, 49±3 e.m.u. Grossular and pyrope are assumed to have susceptibilities of nil.

Thomas Pennant was born at Downing, Whitford, near Holywell, in 1726. A contemporary and correspondent of Linnaeus and Buffon, he is well known to zoologists as a pioneer of British zoology, and to him were addressed the letters of Gilbert White which form the greater part of 'The Natural History and Antiquities of Selborne'. He travelled very extensively in the British Isles and wrote many accounts of his tours, perhaps the best known being his account of London and his 'Tour in Wales'.