Medvedevite, KMn2+V5+2O6Cl⋅2H2O, is a new mineral discovered in the Toludskoe lava field, formed during the 2012–2013 Tolbachik fissure eruption. The mineral occurs as thin acicular transparent bright red crystals up to 0.15 mm. Medvedevite is associated with thénardite, halite, aphthitalite, leonite, kieserite, eugsterite and syngenite. The empirical formula calculated on the basis of 13+ positive charge units for the anhydrous part and 2H2O is (K1.02Na0.03)Σ1.05Mn2+0.95(V5+1.92S6+0.05Si0.04)Σ2.01O6.02Cl0.96⋅2H2O. The crystal structure of medvedevite was determined using single-crystal X-ray diffraction data: monoclinic crystal system, the space group is P21/c, a = 7.1863(2), b = 10.1147(3), c = 12.7252(4) Å, β = 106.243(3)°, V = 888.04(5) Å3, Z = 4 and R1 = 0.029. The concept of ‘structural unit’ and ‘interstitial complex’ could be applied to the crystal structure of medvedevite. The structural units in medvedevite are based on the high bond-valence V5+O5 polyhedra which share edges and link into [V2O6] chains elongated along the a axis. The interstitial complexes consist of Mn2+, K+ cations and H2O groups and occupy the interstices between structural units. The mineral is optically biaxial (+), with α =1.782(2), β = 1.786(2), γ = 1.792(2), 2V(calc) = 41° (λ = 589 nm). The seven strongest lines of the powder XRD pattern are [d, Å (I, %) (hkl)]: 7.79(100)(011); 5.70(11)(110); 4.75(14)(11$\bar{2}$); 3.89(29)(022); 3.25(53)(031); 2.958(79)(21$\bar{3}$); and 2.850(33)(220). The mineral has been named in honour of the Russian geologist and chemist Robert Alexandrovich Medvedev (1939–2005).

Clino-suenoite, ideally □${\rm Mn}_{2}^{2 +} $Mg5Si8O22(OH)2 is a new amphibole of the magnesium-iron-manganese subgroup of the amphibole supergroup. The type specimen was found at the Lower Scerscen Glacier, Valmalenco, Sondrio, Italy, where it occurs in Mn-rich quartzite erratics containing braunite, rhodonite, spessartine, carbonates and various accessory minerals. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is: ANa0.04B(${\rm Mn}_{1.58}^{2 +} $Ca0.26Na0.16)Σ2.00C(Mg4.21${\rm Mn}_{0. 61}^{2 +} {\rm Fe}_{0.04}^{2 +} $Zn0.01Ni0.01${\rm Fe}_{0.08}^{3 +} $Al0.04)Σ5.00TSi8.00O22W[(OH1.94F0.06)]Σ=2.00. Clino-suenoite is biaxial (+), with α = 1.632(2), β = 1.644(2), γ = 1.664(2) and 2Vmeas. = 78(2)° and 2Vcalc. = 76.3°. The unit-cell parameters in the C2/m space group are a = 9.6128(11), b = 18.073(2), c = 5.3073(6) Å, β = 102.825(2)° and V = 899.1(2) Å3 with Z = 2. The strongest ten reflections in the powder X-ray diffraction pattern [d (in Å), I, (hkl)] are: 2.728, 100, (151); 2.513, 77, ($\bar 2$02); 3.079, 62, (310); 8.321, 60, (110); 3.421, 54, (131); 2.603, 42, (061); 2.175, 42, (261); 3.253, 41, (240); 2.969, 40, (221); 9.036, 40, (020).

John Henry Heuland, Fellow of the Geological Society, mineral collector and dealer of 25 King Street, St. James's, London, was born in 1778. He moved in 1839 to 31 Red Lion Square, London, where he remained until after 1850. Few details of his life are known, but his sale catalogues and his intense activity as a collector and dealer during the period when it was fashionable to form collections of minerals have secured him an important place in the historical archives of mineralogy.

In what year Heuland began to deal in minerals is uncertain, but it was before 1804 when we have a record of his buying in Lisbon. He subsequently travelled through France, Germany, Sweden, and Russia, collecting and buying minerals wherever possible. About the year 1806 he came into the possession of a fine collection of nfinerals which had been formed on the Continent between the years 1766 and 1806 by his uncle Mr. Jacob Forster.

Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basichydrology. O’Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile.

Although zinekenite and wolfsbergite are to be considered as isomorphous, it seems to be as rare a thing to find simple crystals of zinekenite as it is to find twinned crystals of wolfsbergite. In the following note simple and twinned crystals of the two minerals respectively are described.

The trace-element assemblage of the cassiterite of the Turkaňk and Rejsy zones of the Kutná Hora mining district are typical of a hydrothermal sulphide-cassiterite formation. Polished section studies show replacement of cassiterite by pyrrhotine, with stannite as am intermediate zone.

The discovery of the meteoric stone near Lake Brown, County Avon, South-West Division, Western Australia, was recorded by Dr. Edward S. Simpson in the Annual Progress Report of the Geological Survey of Western Australia for 1921 (1922, p. 53). The following details concerning the meteorite are taken from that report and from a letter of September 25, 1925, sent by Dr. Simpson with the specimen, weighing 174 grams, which was presented to the British Museum collection by Mr. A. Gibb Maitland, at that time Government Geologist of Western Australia.

At the Society's Anniversary Meeting of November, 1908, I exhibited and gave an account of an unnamed crystal from the dolomite of the Leugenbach quarry in the Binnenthal, Switzerland. In the notice of this meeting, as given in ‘Nature’ of December 10, 1908 (vol. lxix, p. 142), this mineral, which could not be identified with any of the sulpharsenites of lead previously described, is referred to as follows :— ‘One of these [black minerals with metallic lustre] is oblique with β = 81° 11′, (100),(101)= 40° 7′, (010),(111) = 5° 26′; it has a perfect cleavage (100), and, like liveingite, exhibits no oblique striations on the planes in the zone [100,001].’ Owing to lack of material, the chemical composition and specific gravity of this apparently new mineral could not be determined.

The dehydration of thomsonite has recently been studied by Mr. M. H. Hey. The work here described was carried out in the Mineralogy Department at Oxford in the years 1925 and 1926. At the suggestion of Mr. Hey the results, though inconclusive by themselves, are now published for comparison with his own, which were mostly obtained by a different method.

The crystals of artificial cassiterite, described below, were produced by volatilization of South African low-grade tin ores. In the sinter-pot method employed, air was blown through a charge of alternate layers of coke and of a 12 % metallic tin concentrate mixed with fine coke. This charge was placed above a basal layer of previously ignited coal. Occasionally sodium chloride was mixed with the concentrate to remove tin as chloride as well as oxide fume. The air-flow was carefully controlled to prevent slagging and was maintained until the evolution of copious fumes of tin oxide, and at times of chloride, ceased.

Optical pyrometer readings on the charges during the experiments gave temperatures of 1050°C. approximately, but it is certain that this value is a grave under-estimate of the actual temperatures in the interior of the sinter-pot.

The mineral carminite was first described by F. von Sandberger in 1850 in a paper which appeared in Poggendorff's Annalen, entitled ‘Carminspath, ein neues Mineral aus der Ordnung der Arseniate’. It occurred near Horhausen, Rhenish Prussia, forming clusters of fine needles of a carmine- to tile-red colour, implanted on quartz, limonite, and beudantite, and accompanied by pyrolusite, clear crystals of mimetite, and an undetermined yellow, earthy mineral. In a subsequent paper in 1858, ‘Ueber den Carminspath,’ he gave the precise locality as the Luise mine, Horhausen, Rhenish Prussia ; and a quantitative analysis, on 0.068 gram by R. Müller, showed the mineral to be an anhydrous arsenate of iron and lead : As2O5, 49.11 ; Fe2O5, 30.29 ; PbO, 24.55 = 108.95. A trace of phosphoric acid was also present.

Attempts to reproduce the X-ray measurements which led W. L. Brown to postulate the existence of monalbite at room temperature were unsuccessful.

The accompanying engraving represents an exceptionally fine group of crystals ofapatite, found in the Untersulzbachthal in Salzburg. The dimensions are those of the original, its colour is white with a delicate tint of mauve. This group is the finest of three of the most magnificent specimens yet found at this or any other locality, the largest one having been deposited in the national collection of minerals at South Kensington, while the third was unfortunately broken.

A rapid and accurate method of determining the density of a mineral has long been sought for by mineralogists and gemmologists. The hydrostatic method gives a high degreeof accuracy, but has the drawback that each estimation occupies about a quarter of an hour so that if some ten to twenty specimens have to be investigated the time taken will be considerable. The use of heavy fluids is rapid, but for finer distinctions a large number of fluids is required and they tend, either from evaporation or chemical change, to become variable, while the Westphai balance is only reliable for fairly large portions of the mineral. Several attempts therefore have been made to develop a balance which will give a direct reading. Most of these such as the Kratschner balance have been based upon Leonardo da Vinci's principle of the bent lever, but generally have not been sufficiently delicate or accurate for small specimens.

Unfortunately nothing is known of the history of this stone. It was found in 1933 by Mr. R. Bedford in the old museum at Port Adelaide in South Australia. Attached to the specimen is a small label with the number 23, and accompanying it was a card giving in faded writing the information '(23) Meteoric stone from Silverton'. The Port Adelaide Museum has been in a neglected condition for thirty years, and recently it has been decided to reorganize it as a Nautical Museum, and to discard all mineral and miscellaneous material.