During an optical examination of many mesolite crystals with a view to a determination of their symmetry, the author was puzzled to find that whereas mesolite has generally been described as anorthic, on optical evidence, he could detect no trace of inclined extinction in the prism zone. A. Cavinato (1926) 1 and G. Ceshro (1909) 3 had already made similar observations. Further study revealed the probable causes of the discrepancies, and as these sources of error, and the precautions necessary for their avoidance, receive little or no mention in the principal text-books, an account of them might be of some use.

During the examination of the basalts of Calciferous Sandstone age which are mapped on the one-inch Sheet 23 (Hamilton, Lanarkshire) Scotland, the peculiarities of zoning exhibited by the porphyritic felspar were studied in some detail. As only a summary of the details is possible in the memoir explanatory of the geology of this Sheet, the description of the zoning is offered here, and some conclusions regarding the magmatic history of the zoned felspars are presented.

Scorodite from Kiura mine, Bungo, Japan, has been known for many years. However, owing to its diversity in crystallographical and optical properties as well as chemical composition from those of other localities there appears to be some doubts as to the identity of the mineral. It has even been suggested to be possibly a new mineral having a composition akin to that of scorodite. Some time ago a number of fine crystals were placed at our disposal by the courtesy of Dr. Kô, in addition to the recent acquisition by our Institute of a few rarely found beautiful druses of the mineral. It will therefore be worth while to describe some of its main features in detail.

Almost any scientific periodical devoted to mineralogy will afford examples of the failure on the part of some workers to realize the limitations of the accuracy of their measurements. Often results are calculated to far more places of decimals than the measurements can possibly warrant. In other instances measurements which show differences quite outside the limits of probable error are regarded as being in good agreement; this last failing applies especially to chemical analyses, which occasionally provide decided evidence against the formula they are supposed to support.

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 Ve Skerries form a small group of rocks situated just over three miles WNW. of Papa Stour on the west coast of the Shetland Isles. Owing to the notoriously troubled state of the surrounding waters a landing can only rarely be ettected on them, and it is not, therefore, surprising that no account of their geology has yet appeared. Through the kindness of Mr. J. Glencorse Wakelin, Secretary to the Northern Lights Commissioners, the writer has been able to examine a large specimen of the constituent rock secured by Mr. Wakelin in 1930, and considered by him to be typical of the group. The results of this examination proved to be of considerable interest and are given below.

In the hand-specimen the rock is seen to be of even texture and medium grain. It is white in colour but is relieved by a few darkgreen or black spots and by very thin veins of haematite. In appearance it is not unlike an aplogranite, but examination under a handlens reveals the absence of quartz, while much of the felspar is seen to be twinned on the albite-law.

Since the early work of Dmde and others on the reflection of light by opaque crystalline media, little progress has been made in the direct determination of the indices of refraction and absorption for such substances. Interest in the optical properties of the opaque minerals, however, has been greatly stimulated by the rapid development in the last few years of the methods of ore-microscopy first brought into prominence by Campbell in 1906. Full theoretical discussions have been given recently by Berek, Koenigsberger, and others, but the only quantitative measure feasible in routine microscopy at present is that of the reflectivity.

Specimens of quartz-muscovite-schist obtained fro: boulders in the Shotover river, western Otago, New Zealand, ere recently examined by the writer and found to contain abundant piedmontite, a mineral not previously recorded from New Zealand. The specimens had been collected twenty years before and were labelled ' micaceous quartz schist coloured with haematite' in the geological collections of the Otago University. The following description is submitted pending further field investigations.

This interesting new mineral was discovered by the first author in February 1933 whilst in the employment of the British South Africa Company Limited as a field geologist to the Rhodesia Minerals Concession Limited under the direction of Dr. J. Austen Bancroft. The locality, longitude 29° 29′ E. and latitude 15° 27′ S., is about eighty miles east of Lusaka, the new capital of Northern Rhodesia, after which the mineral is named. The central African plateau has here been cut back from the northern escarpment of the Zambezi rift valley, about 10 miles to the south, producing a rugged topography varying from 1,000 feet to 4,000 feet in altitude.

Among a number of specimens which the senior author (J. l)rugman) obtained some years ago from the widow of a mine manager, Mr. Legrand, of Belgian nationality, was one of massive blendc from the Flor de Peña mine, Lampazos, Nuevo Leon, Mexico, which carried a small quantity of a bright yellow, transparent substance that could not be identified with any known mineral. Goniometric and optical examination showed it to be monoclinic, but the material was mainly massive radiating-prismatic, and the few freely developed crystals gave only very approximate measurements (see table II). A chemical analysis by the iunior author showed it to be indeed a new mineral, a basic zinc arsenate, and the name ‘legrandite’ is proposed for it in recognition of the collector. The larger part of what remains after investigation of the small specimen has been presented to the British Museum for preservation in the mineral collection.

In 1890, L. V. Pirsson 2 described under the name of mordenite a crystalline mineral, isomorphous with heulandite, occurring in a highly weathered amygdaloidal basalt in the Hoodoo Mts., Wyoming. His analysis (1, table I) showed that the mineral had a composition near that of the original mordenite of H. How (1864) and his assumption that it represented a platy-crystalline phase of that normally fibrous mineral was generally accepted.

In 1910 in volume 15 of this Magazine I was able to place on record some details respecting the 'Cullinan' diamond from South Africa, the largest crystal of diamond yet found. I have now been able to collect some information about the largest known meteorite. The facts concerning remarkable obiects such as these are apt to become exaggerated and distorted, and it is well to place on record the true and accurate data while they can still be ascertained.

The rare mineral stichtite, a complex hydroxy-carbonate of magnesium, chromium, and iron, was defined in 1910 by W. F. Petterd on material from the Adelaide silver-lead mine, Dundas, Tasmania. Petterd's description, together with detailed optical and chemical studies by A. S. Wesley, L. K. Ward, L. Hezner, and A. Himmelbauer, were collected by W. H. Twelvetrees and issued by the Tasmanian Department of Mines in 1914. A new analysis of the Tasmanian material is included by W. F. Foshag in his investigation of the hydrotalcite group.

The mineral was next recorded by E. Poitevin and R. P. D. Graham from the Megantic mine, Black Lake area, Quebec; no chemical data of this occurrence are available.

In two-circle goniometry as usually practised, the zone-adjustment is almost invariably used. It would be difficult to discover the reasons which have led to this unfortunate neglect of the face-adjustment; actually the face-adjustment has all the advantages of the zone-adjustment without its defects.

Though calcium hydroxide has long been known as a product of hydrolysis of Portland cement, reliable data on its physical and optical properties were not available until Ashton and Wilson prepared this substance artificially and had examined crystals developed in rugs in old cement briquettes. In examining some recently collected larnite-spurrite-rocks from Scawt Hill the writer observed crystals now shown to be Ca(OH)2 as constituents of aggregates composed mainly of coarsely grained afwillite, forming infillings in these contact-rocks.

Although a considerable amount of work has been published On the occurrence and crystallography of fluorite, comparatively little has been done on the variations in habit of the crystal s. V. Goldschmidt's 'Atlas der Krystallformen' (vol. 4, 1913) gives 160 drawings with references for different forms and combinations of fluorite, but very few attempts have been made to explain the different habits observed. Experiments on the artificial growth of crystals by different methods; under varying conditions of temperature and pressure, and in the presence of foreign substances in the solution do not appear to have been made.

An occurrence of silica-glass in lumps up to 10 lb. in weight, smaller fragments being scattered over an area at least 80 by 25 kilometres, has been discovered in the course of the work of the Egyptian Desert Surveys. A Survey expedition under Mr. P. A. Clayton was sent out in December 1932 to work in the unexplored area of the Sand Sea and Gill Kebir, west of Major R. A. Bagnold's 1930 route, and found the glass on December 29, 1932.

One of the most typical occurrences of natrolite, in the Puy-de-Dôme amygdaloids, formed the main type occurrence of R. J. Haüy's species Mcsotype (1801) ; but when A. F. Gehlen and J. N. Fuchs (1813) and J. N. Fuchs (1816) recognized the individuality of soda-, lime-, and lime-soda-mesotypes, and divided Haüy's species into three, they discarded Haüy's name altogether, using for the three new species the names natrolite, scolecite, and mesolite, Natrolite was not a new name, having been given in 1803 by M. H. Klaproth to the well-known yellow-banded fibrous-radiating zeolite from Württemberg. The name mesotype has persisted for the whole group (in which sense it will be used here); and for long the names soda-, lime-, and lime-soda-mesotype were used as well as Gehlen and Fuchs's names. In France, however, the name mesotype is used in a more restricted sense for natrolite only.

In a further search for portlandite amongst the vug minerals of the Scawt Hill contact-zone, attention was drawn to some infillings containing a mineral which had not previously been observed. These infillings, which occur in a larnite-rock carrying melilitewollastonite aggregates of the hybrid zone of the contact, consist of afwillite, portlandite, ettringite, and aggregates of a mineral, the light-greenish colour of which was conspicuous.

In the early part of 1931 public interest in South Australia was stimulated by the fall of the Karoonda meteorite on November 25, 1930, and its subsequent discovery by an Adelaide University party led by Prof. Kerr Grant. In consequence of this Prof. Grant was informed separately by Mr. B. Bowman of Tempe Downs and Mr. J. M. Mitchell of Oodnadatta that fragments of meteoric iron were to be found surrounding several crater-like depressions near Henbury Cattle Station in Central Australia. The number of craters was variously described as three and five.