About two years ago there was brought to the British Museum a specimen covered with numerous mall cubes—so the crystals appeared to be—of the bluish-green colour suggestive of a mineral containing copper. Judged by their form the crystals might be beleito, but a qualitative analysis by Dr. Prior, while revealing the presence of chlorine and copper, showed no trace of lead. A crystal was then removed from the specimen and measured on a goniometer, and the discovery was at once made that these apparent cubes are iu reality rhombo-hedra with an angle of nearly 88° between adjacent faces. Since no previously known oxychloride of copper crystallizes in this form, these crystals were evidently worthy of further investigation.

The rock-specimens here treated were collected in 1902 on a small plateau near the head of the Oberer-Bach, where the rock is in place. This stream, rising near the Röckner or Reckner, a summit of the Tarnthaler-Köpfe on the north of the Tuxerthaler mass, flows down a steep ravine southward to join the Schmirner-Bach: the locality is situated about 20 kilometres to the south-east of Innsbruck. The figures 2629 (height in metres) on the ‘Generalstabskarte’ probably represent the site of the plateau ; it is on the right bank of the stream, close to, and some 12 or 15 metres above, a small frozen lake near the head of the stream. The point was reached by ascending the ridge from the Kreuzjöchl. There was much snow on the plateau and the geological relations of this particular occurrence were not observed.

During the summer of this year certain crystals of zirkelite from Ceylon were entrusted to the author for crystallographical investigation, and in that connexion the specimens placed under this species in the British Museum collection were examined for the sake of comparison. The whole of the latter specimens come from Jaeupiranga in São Paulo, Brazil: some of them had been presented by Dr. E. Hussak and formed part of the material on which he and Dr. G. T. Prior conducted their investigation which led to the first discovery of zirkelite, while the remainder were purchased subsequently. The latter included a lot of small, brilliant crystals (numbered 86034 in the General Register) which differed so markedly in lustre from the other crystals as to suggest that they had been incorrectly determined.

Let the crystallographic axes OA, OB, OC of a crystal, whose axial ratios are a : b : c, meet a plane p in A, B, C. Let a plane through O, parallel to a crystal-face whose indices are h, k, l, meet p in the line f (fig. 1) ; and let the line OF, perpendicular to the face, meet p at the point F. Let the perpendicular from O on p meet it in V, and let OV = m.

The mass of meteoric iron brought Dora Patagonia in 1896 by Dr. Francisco P. Moreno, Founder and Director of the State Museum of La Plata, had been sought for by him, while exploring that region, because of a reference which had been made to it in Captain G. C. Musters's book, ‘At Home with the Patagonians,’ published in 1871.

Dr. Moreno believed the mass to be really identical with a block of supposed marble, referred to on page 87 of that work as having been seen by Captain Musters in 1869 at Amakaken, which is situated in longitude 71° 56′ W. and latitude 48° 10′ S.

The mineral to be described was found by Mr. C. T. Clough, M.A., of the Geological Survey, near the junction of the two large streams in Coire Dhorrcail, near Barrisdale on the south side of Loch Hourn, Inverness-shire.

Mr. Clough furnishes me with the following description of the mode of occurrence of the mineral :—

‘The crystals were obtained from a band, which, although its sides are not well exposed, seems to form a nearly horizontal vein-like mass. This band crosses both the bedding and the foliation planes of the muscovite-biotite-gneiss in which it occurs, and which occupies a large area near Barrisdale and Ladhar Bheinn.

A small collection of minerals, together with other natural history specimens, has recently been acquired by the British Museum from the Rev. A. North Wood, a missionary in the Usagara (Ussagara) province of German East Africa. Mr. Wood's station is situated at Itumba, and the specimens had been brought o him by the natives from the surrounding district, mainly from places between Mamboya and Mpapwa, which lie on the caravan route from the coast opposite Zanzibar westwards into the interior to Lake Tanganyika.

The rocks of the district are biotite-gneiss and hornblende-gneiss, the latter with small garnets.

Some years ago the writer received from St. Joseph du Lac in the County of Two Mountains, province of Quebec, Canada, a few small specimens of a black mineral which was identified as magnetite. Later, a more careful inspection of the fragments, which weighed from tell to fifteen grams each, showed that some of them were portions of crystals made up of an unusual combination, the octahedron {111} and a trapezohedron {311}. Further, chemical analysis showed that the composition was specially interesting, the mineral being titaniferous and containing, besides 3.24 per cent. of magnesia, a larger proportion of manganese than had been observed in the case of anymagnetite previously examined.

Considerable confusion exists with regard to the nomenclature of the thirty-two possible classes of symmetry and their classification into systems. Each class is usually denoted by a name and a symbol ; but as every author invents his own names and symbols (the latter being often merely arbitrary numbers) the whole nomenclature is hopelessly confused. This is due to the fact that a different classification into systems, and consequently a different nomenclature is suggested according as the subject is approached (1) from the geometrical aspect based on the law of rational indices alone, (2) from the aspect of the structure-theory, (3) from the aspect of the practical crystallographer. Thus, for example, Dr. A. Schoenflies finds two distinct classifications necessary according as the subject is approached from aspect (1) or (2).

Some small isolated crystals from the gem-washings in Ceylon, recently sent by Mr. A. K. Coomáraswámy to the British Museum for determination and study, were at first thought to be rutile, but on detailed examination proved to be zircon of a rather unusual type. This has a specific gravity of 4.0, which is not increased when the crystals are heated.

The majority of the crystals are from the Balangoda district in the Sabaragamuwa province, and, according to Mr. Coomáraswámy have been derived from a group of zircon-granites which occur in this district; a few others are from Walaweduwa in the Bamberabotnwa district, and from the Hatton district. Associated with them are zircons of more usual types (see p. 48); the present description is, however, confined to the crystals of lower specific gravity.

Some very brilliant and well-modified crystals of ilmenlte, recently found in the neighbourhood of the Ofenhorn, are of interest in that they exhibit a well-marked parallel hemihedrism and show the presence of a number of new forms. Although constantly sought for, it is more than fifteen years since crystals of this mineral were last found in the Binnenthal. The crystals described by H. Bücking in 1877 appear to differ in habit from those of the new find.

During recent years a systematic survey of the mineral resources of Ceylon has been in progress, in connexion with which a large number of specimens have been sent to the Imperial Institute for examination. In 1905 several cases containing coarse gravel from the streams of the gem-district of Balangoda were received. The constituent minerals were mainly zircon, tourmaline, corundum, spinel, ilmenite, together with small quantities of geikielite, fergusonite, and other rare-earth minerals. Last summer during the examination of these gravels one of the authors found three black crystals witll unusually brilliant faces. The apparently monoclinie form and the general physical characters at once suggested the crystallized native zirconia, baddeleyite, and this conjecture was confirmed by the goniometrical measurements and the chemical analysis.

The diagram (Plate III), to which for convenience the author has given the name moriogram, is intended to provide a method for rapidly determining the angles between a face of symmetry and all other faces with rational indices, which lie with it in some particular zone, when two of the angles are known, or, what is precisely the same thing, between a zone of symmetry and all other zones with rational indices, which intersect it in the same pair of opposite poles, when two of the angles are known : whenever possible it should be arranged that one of the known angles is a right angle. The meriogram may, therefore, be used in the course of computation for checking the accuracy of the work, or during the goniometrical measurement of a crystal for finding the relations subsisting between the faces or the zones.

The deposit known as the Wheal Sedgman lode is inclined to the west a few degrees from the vertical, and runs in a direction about 10° W. of N. (magnetic) through the parish of Perran Uthnoe, near Marazion, Cornwall. In its course seawards from the approximately E. and W. lode formerly worked in the Great Wheal Neptune mine, it traverses the North and South Trebarvah tin and copper lodes. It is crossed by the shore-line on Perran Sands, about 500 yards to the west of Trevean cliff. Between that spot and Cuddan Point, to the S.E., where it is again laid bare, it has been superficially removed by marine denudation. The numerous N. and S. diabase dikes of the district show in placts much disseminated pyrrhotite, and one of them runs nearly parallel to the east side, or foot wall, of the Sedgman lode.

Some months ago Professor Henry Louis presented to this college several isolated crystals which he had brought from the Sulitjelma (or Sulitelma) mines in Arctic Norway: they occur there in masses of copper-pyrites and iron-pyrites, for which this district has been famed for some years.

The crystals are of various sizes, ranging in length from 4 to 8 mm. They have a metallic lustre and silver-white colour. The fracture is uneven, and no cleavage is visible. On a freshly broken surface small yellow particles can be seen with the naked eye; these also have a metallic lustre, and are probably iron-pyrites, a probability which is strengthened by the appended chemical analysis. The specific gravity varies from 5.94 to 6.02, and the hardness is just under 5. The crystals are all of a pronounced rhombic aspect.

A determination of the refractive power, which need be accurate to the second place of decimals only, is of considerable service for the discrimination of transparent substances, such as, in particular, faceted gem-stones. If the substance be so highly refractive that a total-reflectometer be not available, the method of minimum deviation is the simplest hat can be used.