In a previous number of the Mineralogical Magazine (1909, vol. xv, p. 260), attention was called to a simple electrostatic method whereby, using a stick of sealing-wax and a copper plate, grains of minerals which have a metallic or sub-metallic lustre can generally be separated from those of the more transparent minerals, the former being attracted notwithstanding the fact that they are usually heavier than the latter.

In the summer of 1906 some large crystals of seligmannite were found in an irregular, elongated cavity in the dolomite-rock of the Lengenbach quarry at Binn, Switzerland. Owing to their brittle nature many of them were broken when the rock was blasted, but I was in the quarry at the time and collected all the fragments. The largest crystal broke after it had been measured, and Dr. G. T. Prior's analysis II was made on portions of it, his other analysis, I, being made on measured crystal fragments found with the large crystal. The streak of the present crystals is black and inclined to purplish in colour, while that of the crystals first described by me was chocolate-coloured.

Hitherto the mineral prehnite has been recorded from one locality only in Cornwall, namely, in the cliffs between Wheal Cock and the Crowns Rock, Botallack, St. Just. It occurs there as pale-green, globular aggregates composed of indistinct, curved crystals, and forms veins traversing a narrow strip of greeustone which has intruded itself through the granite mass; associated minerals are stilbite and axinite.

In the summer of 1910 the writer collected several crystallized specimens of this mineral at Pare Bean Cove, Mullion, the locality from which Dr. J.S. Flett and Mr. W. F. P. McLintock obtained the fine crystallized specimens of datolite, recently described by the latter. The prehnite occurs here in two distinct and somewhat unusual types of crystals—tabular and prismatic.

On October 22, 1903, a considerable shower of meteoric stones occurred in the neighbourhood of the village of Dokáchi, situated near the mouth of the Ganges, in the Dacca district of Bengal. Seven of these stones, which had been obtained flom natives on the spot by Mr. H. E. Stapleton, M.A, of St. John's College, Oxford, Inspector of Schools in the Dacca district, were recently presented by him to the Oxford Museum.

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'.

There occurs frequently in coal a white carbonate which, when it is referred to at all by scientific writers on coal, is usually described as calcium carbonate. It occurs as a rule in the form of thin layers infilling the joint-cracks which lie normal to the bedding-planes, though at times it may be seen infilling other divisional planes which may cut across the bedding obliquely.

In the year 1904, two specimens were sent to me by Mr. F. H. Batler for determination, which showed small, colourless, rhombie or oblong tabular crystals on granite. The crystals proved on examination to be the beryllium silicate bertrandite, which forms a new addition to the list Of British mineral species.

This mineral was first described by E. Bertrand in 1880 from the quarry of Petit Port, near Nantes, and it has since been found at other places in the same neighbourhood as well as in the old tin-workings at La Villeder in Morbihan, and near Alençon and Limoges, though always in very small quantity. Outside France it has been found only in the neighbourhood of Pisek in Bohemia ; and, in tile United States, at Stoneham and elsewhere in Maine, Amelia Court House in Virginia, and on Mt. Antero in Colorado.

Examples of quartz twinned on a face of the primary rhombohedron R are extremely rare. Only three isolated examples have so far been recorded. The first was observed by Q. Sella; but as his crystal could not be measured, owing to its position on the matrix, it is of only slight importance as evidence of this mode of twinning of quartz.

As is well known, the dolomite of the Lengenbach quarry is rich in pyrites and has some rutile.; the crystals of the latter being very small and somewhat infrequent. It seems therefore strange that the presence of hematite or ilmenite has not hitherto been recorded. This last summer I obtained a specimen which showed a minute black crystal with numerous faces, which I began examining under the impression that it was a sulpharsenite.

Nearly ten years ago, in 1902, five small crystals were noticed by one of us on a crystal of a sulpharsenite of lead, probably rathite, which had been found in the Lengenbach quarry that summer. Although from their lead-grey colour they also appeared to belong to a sulpharsenite of lead, in habit and appearance they were unlike the crystals of any such species as yet known. The crystals were measured, and were shown at the anniversary meeting, of the Society, November 18, 1902, but the measurements were not published at the time in the expectation that further material would afterwards be found which would enable an analysis to be made and perhaps throw fresh light on the morphological characters of the crystals.

The mineral dealt with in this paper was sent for examination the Imperial Institute by Mr. J. B. Scrivener, Government Geologist to the Federated Malay States. It occurs on the river Sebantun, about half a mile above Salak North village, Kuala Kangsar district, Perak. The ground on which it was obtained was held on a tin-mining lease, but had to be abandoned owing to the presence of the unknown mineral, which rendered mining unprofitable.

A crystalline deposit of sufficient interest to warrant description was brought to the authore notice by Mr. Henry Preston, F.G.S., who has recently described its mode of occurrence. The material consists of a white, glistening, crystalline powder, or a sand-like aggregate of minute crystals. It was deposited in a water-tank into which water was led through an old leaden pipe, over a mile in length, from a spring rising from the basal ferruginous beds of the Marlstone (Middle Lias) ill Belton Park, north of Grantham, Lincolnshire. The sand was deposited in the tank as a conical heap, spreading over a base of perhaps four square yards and reaching a height of seven or eight inches at its summit.

Last year (1911) the Trustees of the British Museum acquired a large isolated crystal of anatase, which is of interest not only on account of its unusual size, but also because of the vicissitudes that, to judge from the furrowed appearance of certain faces, it had undergone in the course of growth. It was by far the largest of the many crystals of this species that were found in the previous year (1910) near the ridge Kollergraben in the district known to early mineralogists as Alp Lercheltini, probably at a spot named Spissen.

The following notes on some peculiar forms of cassiterite found in the Malay Peninsula will, it is hoped, prove of interest and an addition to our knowledge of the mineral.

It is now well known that the most effective method of separating wolframite from eassiterite on a commercial scale is the electromagnetic process, which, in theory, lifts all the wolframite from the ore and lèaves a concentrate of cassiterite. In practice, however, the separation is rarely, if ever, perfect; and it has been possible for the writer to obtain some interesting information bearing on the point, the most valuable being the discovery of a few specimens of cassiterite that may be termed magnetic in that it can be lifted by an electromagnet.

There are probably few subjects for the study of which models are more indispensable than the theories of crystal structure ; but the provision of any considerable series of such models is costly, and they require, moreover, a large amount of space for storage. Some interchangeable models, which the author has lately had constructed to illustrate the space-lattices and the regular point-systems of Sohncke, and which may be fitted up and taken to pieces as required, have been found so convenient, both for lectures and for private study, that a short description of them may be found useful, although they differ only in details of construction from those suggested by Sohncke.

Although topaz and beryl have been previously recorded from Lundy Island, no account has hitherto been published of their characters and mode of occurrence. In the summer of last year a geological survey of the Island was commenced by one of us, and during the progress of the work good crystals of these minerals were obtained, the results of an examination of which it seems desirable to place before this Society.

The relationship between the optic axes and the vibration-directions in a section of a biaxial crystal was enunciated by Biot in 1819, and may be stated as follows : The vibration-directions in any section of a biaxial crystal are given by the bisectors of the angles between the optic axes as projected on the plane of section.

Dr. Fletcher and Mr. Harker have elaborated the idea, but there appears to be room for a simpler presentment, more adapted to the needs of students, which does not involve the use of the optical indicatrix or the spherical projection.

Mallard's original method was based on the measurement of the linear distance, as determined by an eyepiece-micrometer, between the optic axes in a section of the crystal at right angles to the acute biseetrix viewed in convergent light.

Professor F. Becke implored on this method by utilizing sections which were not at right angles to the acute hissetrix, but in which both optic axes were visible in the field. He projected both axes by means of an Abbe camera lucida on to a revolving drawing-table, and by means of the Mallard equation plotted the axes on a stereographic projection and thus obtained the optic axial angle, the angles of course being corrected for refraction to the true angles in the crystal section. Professor Becke subsequently, by utilizing the Biot-Fresnel law, formulated a graphic method of obtaining the optic axial angle from a section in which only one axis was visible.

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 mineral phenacite (beryllium ortho-silicate) has not previously been recorded from the British Isles. The following notes contain an account of its characters and mode of occurrence at five distinct localities in Cornwall. The occurrences are described in the order of their discovery.

During the early part of 1905, while examining the Cheesewring Quarry, in company with Mr. F. H. Butler, who on a previous visit had discovered bertrandite at this locality, I paid special attention to the diseovcry, if possible, of any other beryllium minerals. I was fortunate enough, after much searching, to find a specimen showing three small crystals that at once suggested the mineral phenacite ; a surmise which On examination proved correct.