When a mineral fragment is brought under the influence of an electrostatic charge, its behaviour depends chiefly upon the conductivity of the mineral and that of the surface on which it is lying. This fact can be effectively demonstrated by placing fragments of amber (sp. gr. about 1.1) and pyrite (sp. gr. about 5) on a metallic surface, such as that of a copper plate, and noting their behaviour when a rod of vulcanite, which has been electrified by rubbing with cat's skin, is brought near them. Under these conditions a small fragment of dry amber, weighing not more than one milligram, is not attracted to the rubbed rod, although the rod be brought almost in contact with it; whilst a large piece of pyrite weighing as much as 150 milligrams jumps visibly from the plate with the rod held at some distance from it.

In mid-1949 the London Natural History Society set up a committee to investigate and record temporary geological sections in the London area. Among the earliest to be dealt with was the excavation in flood-plain gravel for the foundations of the Concert Hall for the Festival of Britain (1951). Samples of 100-200 grams were taken from two sandlentieles for heavy mineral investigation, and material from one of these, passing 60 mesh and washed by laevigation, yielded, on separation by means of a bromoform-benzene mixture of density about 2"73, an assemblage with abundant garnet, tourmaline, zircon, and kyanite, very occasional staurolite, cassiterite, and fluorite, and moderately abundant collophane.

The potash feldspar in the charnockites is orthoclase and they are inferred to have been formed around 700 °C. A twin-law study of the plagioclase indicates an igneous origin of the charnockites and pyroxene granulites. The KD values of the coexisting pyroxenes in the granulites are appropriate to equilibrium at 670 °C. A substantial substitution of A1 for Si in the values of the coexisting pyroxenes in the granulites are appropriate to equilibrium at 670 °C. A substantial substitution of A1 for Si in the Z group in all mafic minerals studied also indicates relatively high temperatures of formation. Almandine is pyroperich, a result of high pressure. The charnockites and pyroxene granulites are inferred to be formed under conditions of high pressure and temperature.

The occurrence of melanterite, pisanite, and chalcanthite as secondary minerals resulting from the oxidation of pyrites masses containing copper is well known. It is not so well known that other metallic sulphates are from time to time found, and a brief description of the mode of occurrence of a few of these, in addition to some details of the composition of pisanite and chalcanflSte, may be of interest.

Pisanite.—This mineral is of common occurrence at all the pyrites mines of Huelva and elsewhere, ibrming stalactites and stalagmites in those parts of the mines that are above drainage level though subject to more or less percolation of water. It is rarely found as well-formed crystals, save occasionally when a pool ef strong sulphate water has been temporarily dammed hack in some way, and then supersaturated through evaporation.

Chemical, X-ray, and optical analyses of eight Ca-rich pyroxenes and three coexisting Ca-poor pyroxenes from the gabbros of the Marangudzi ring complex, Rhodesia, are presented. Both the series show limited Fe-enrichment. High Ca-content of the clinopyroxenes together with their restricted Fe-enrichment, having a trend from Ca44·8Mg42·6Fe12·6to Ca42·7Mg37·7Fe19·6, could be indicative of an alkaline nature. But the presence of a Ca-poor pyroxene phase with a compositional trend between Ca2·9Mg71·2Fe25·9 and Ca3·1Mg63·0 Fe34·9 onwards in small amounts suggests tholeiitic to calc-alkaline nature. Certain characteristics in the variation in composition of the pyroxenes confirm a transitional nature of the Marangudzi parent magma, originating at a depth comparatively greater than the normal tholeiitic magma, but less deep than alkaline magma, at a fairly high pressure. The Marangudzi pyroxenes are compared with the pyroxenes of the similar world-wide igneous complexes.

The metallic grey minerals which are found in the white saceharoida! dolomite of the Binnenthal have been known ever since the old priest Walpen of Binn and R. yon Ritz began collecting them nearly seventy years ago.

The name "binnite" was first given indiscriminately to the grey metallic minerals; afterwards these were subdivided into "Kugel Binnit" and " Stangen Binnit."

Anyone who contemplates on a map the great size of this island in geographic extension, and its extraordinarily irregular outline, would conclude that it must be composed of various formations, and that the connections and dispositions of these must be intricate in the extreme.

The latter conclusion will, however, upon a more careful observation, be found to apply only to the western portion of the island. However deeply trenched by the sea iu its lower grounds, however persistently thrusting its cliffs oceanward in its higher, the ridged and furrowed outlines of the eastern, disposed in almost rectilinear sequence, indicate but one formation,—various as the members of that formation may in mere lithological features appear.

During the investigation of a migmatite complex near Strathy, north Sutherland, cummingtonite and gedrite were found to be common constituents of certain schists and granulites. Calcium-poor amphiboles have not hitherto been recorded from rocks of the Moine Series, and it is the purpose of this paper to give the results of the optical and chemical study of three examples of this group. The methods of separation and purification employed are described in some detail as it is considered that many of the previous analyses of these minerals are vitiated by faulty procedure. To avoid errors in separating two amphibole species, the investigated samples were taken from rocks containing a single amphibole phase. The paper concludes with a discussion of the correlation of optical properties and chemical composition of cummingtonites and gedrites.

In the memoir dealing with the geology of the Broken Hill district, New South Wales, mention is made 1 of a remarkable rock type found in a few places in the vicinity of Broken Hill, which looks not unlike an aplite in the field. A brief description of its appearance in thin section is given. It consists mainly of what appears to be very basic plagioclase. A fair amount of quartz, some epidote and bluishgreen hornblende were noticed, whilst a notable amount of sphene is present.

We have characterized the crystal structure of natural kutinaite, a rare mineral from the ores of Černý Důl, Czech Republic, by single-crystal X-ray diffraction and chemical analysis. We found that the structure of natural kutinaite is not identical to that of synthetic Cu14Ag6As7, previously reported to be cubic, space group Pm3m. Although topologically similar, the structure of natural kutinaite is indeed tetragonal, space group P4/mmm, with cell parameters: a = 11.789(2), c = 11.766(2) Å, V = 1635.5(4) Å3 and Z = 4. Electron microprobe analyses pointed to the (K,Tl)0.25Cu14Ag6As6.75 stoichiometry (Z = 4), or (K, Tl)Cu56Ag24As27 with Z = 16. The crystal structure of an untwinned crystal has been refined to R1 = 2.61%. It consists of clusters of eight edge-sharing tetrahedra of Cu, which alternate in a 3D chess-board manner with octahedral clusters of six Ag atoms. The latter are surrounded by triangularly coordinated copper in eight faces of a cuboctahedron. The last structure components are large cavities containing partly occupied (K,Tl) sites, coordinated by 18 Ag and As ligands. The structure is full of direct metal-metal contacts although As plays the role of anion, associating especially with copper.

In the course of an investigation of the atomic weight of nitrogen Mr. F. P. Burt, of University College, London, prepared by the following process crystals of nitrogen sulphide, N4S4, surpassing in purity any that had been previously obtained. The nitrogen sulphide was recrystallized from benzene, washed with carbon disulphide to remove as much sulphur as possible, and finally washed with a little cold benzene. The product was powdered on a porous tile, and kept in a desiccator with calcium chloride and cocoa-nut charcoal until it no longer smelt of benzene. It was then sublimed in vacuo over silver gauze heated to 100° C. in a steam-jacket, by which means the absence of liquid or gaseous inclusions and of free sulphur in the sublimate was assured.

Notwithstanding the very considerable extent of shore-line which the deepest-seated rock exposes to the ocean, it exhibits extremely few illustrations of either cliff, or rocky shore.

The rocks which do occur are found to be of an altitude which is altogether trifling,—very much more so than even the great durability of the material of which they are composed would warrant us in expecting. Indeed, from the fact of the shore-line being at right-angles to the strike of the strata, and from these strata being at so high an angle of tilt, we should expect to meet with an almost continuous line of cliff. Instead of this, we find long points of land, of hummocky or undulating contour, running far out into the sea,—a profuse sprinkling of cliffless islets, which resemble in every particular the hummocks of the land,—and long sinuous stretches of water thrusting themselves up into what resemble land-valleys, very much more than sea-bays.

Ultrahigh-pressure and -temperature (P-T) experimental techniques have progressed rapidly in recent years. By combining them with X-ray diffraction measurements at synchrotron radiation facilities, it is now possible to examine deep Earth mineralogy in situ at relevant high P-T conditions in a laser-heated diamond anvil cell (DAC). The lowermost part of the mantle, known as the D″ layer, has long been enigmatic because of a number of unexplained seismological features. Nevertheless, the discovery of a phase transition from MgSiO3 perovskite to ‘post-perovskite’ above 120 GPa and 2400 K indicates that post-perovskite is a principal constituent in the lowermost mantle, which is compatible with seismic observations. The ultrahigh P-T conditions of the Earth’s core have not been accessible by static experiments, but the structure and phase transition of Fe and Fe-alloys are now being examined up to 400 GPa and 6000 K by laser-heated DAC studies.

A twin-law study of the plagioclase indicated metamorphic origin of the charnockites and volcanic origin of the basic members of the charnockite series. The original volcanic products have been influenced by the later metamorphism, resulting in the various basic members. The twinning in the plagioclase is considered to be primary. The perthite in the charnockite is of orthoclase variety and indicates a higher temperature of formation than the charnockites of other areas containing microcline. The orthopyroxene in the charnockite series is hypersthene and the clinopyroxene is sahlite. Hypersthene is inferred to have formed at the expense of sahlite, hornblende, biotite, and garnet.

Professor Baumhauer, in January, 1901, described five very small crystals of a new mineral, to which he gave the name seligmannite. They were associated with rathite and binnite in dolomite, and came from the Lengenbach quarries in the Binnenthal, Switzerland. In June, 1902, he described another crystal, the angles of which agreed fairly well with those of the crystals he had previously measured. In habit and twinning, these orthorhombic crystals so closely resembled bournonite that he ventured to assign to the new mineral the chemical formula Cu2S.2PbS.As2S3, but from paucity of material he was unable to make a chemical analysis.

The new mineral currierite (IMA2016-030), Na4Ca3MgAl4(AsO3OH)12·9H2O, was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, canutite, chudobaite, halite, lavendulan, magnesiokoritnigite, quartz, scorodite and torrecillasite. Currierite occurs as hexagonal prisms, needles and hair-like fibres up to ∼200 μm long, in sprays. The crystal forms are ﹛100﹜ and ﹛001﹜. Crystals are transparent, with vitreous to silky lustre and white streak. The Mohs hardness is ∼2, tenacity is brittle, but elastic in very thin fibres, and the fracture is irregular. Crystals exhibit at least one good cleavage parallel [001]. The measured density is 3.08(2) g cm -3 and the calculated density is 3.005 g cm -3. Optically, currierite is uniaxial (–) with ω= 1.614(1) and ε= 1.613(1) (measured in white light). The mineral is slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobe analyses, is (Na3.95A12.96Ca2.74Mg1.28Fe0.633+Cu0.13K0.08Co0.03Σ11.80 (AS11.685+Sb0.325+Σ12(O56.96Cl0.04)Σ57H30.81. Currierite is hexagonal, P622, with a = 12.2057(9), c = 9.2052(7) Å, V= 1187.7(2) Å3 and Z = 1. The eight strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 10.63(100)(100), 6.12(20)(110), 5.30(15)(200), 4.61(24)(002), 4.002(35)(210), 3.474(29)(202), 3.021(96)(212) and 1.5227(29)(440,334,612). The structure of currierite (R1 = 2.27% for 658 Fo > 4σF reflections) is based upon a heteropolyhedral chain along c in which AlO6 octahedra are triple-linked by sharing corners with AsO3OH tetrahedra. Chains are linked to one another by bonds to 8(4 + 4)-coordinated Na and 8-coordinated Ca forming a three-dimensional framework with large cavities that contain rotationally disordered Mg(H2O)6 octahedra. The chain in the structure of currierite is identical to that in kaatialaite and a geometrical isomer of that in ferrinatrite. The mineral is named in honour of Mr. Rock Henry Currier (1940–2015), American mineral dealer, collector, author and lecturer.