Leonard James Spencer, Keeper of Minerals in the British Museum (Natural History) from December 1927 to July 1935, joined the Department of Mineralogy officially on January 1, 1894, filling a vacancy caused by the death in 1892 of Thomas Davies. Davies had served in the Department since 1857. Trained by Nevil Story- Maskelyne, Keeper from 1857 to 1880, he had taken a great share in the arrangement and labelling of the mineral collection and in his later years had also had charge of the collection of rocks. Spencer was almost equally well qualified as a petrologist and as a mineralogist. He had studied chemistry at the Dublin Royal College of Science before going to Cambridge, where he studied geology as well as mineralogy and chemistry and gained the Harkness Scholarship for Geology in 1893. The examination for the vacancy at the Museum was held in August 1893 and Spencer was the successful candidate.

The association of clay minerals with sillimanite near Williamstown, approximately 23 miles north-east of Adelaide, South Australia, has been noted by the writer in earlier papers (Alderman, 1942, 1950). These papers described the occurrence of quartz-sillimanite and quartz-kyanite rocks and gave the evidences which suggest that they were formed metasomatically by alumina-rich fluids at high temperatures. It was also suggested that as the alumina-concentration and temperature of the fluids decreased the metasomatic activity was followed by a period of pegmatitc formation which, in turn, gave way to a hydrothermal stage. Brief reference was made to the conversion of sillimanite to clay by hydrothcrmal agencies.

There are many basic copper chlorides and sulphates which occur as minerals but have received little recent crystallographic study. Yet copper is a widely distributed element and many of these minerals are the products of corrosion and weathering of bopper and copper ores.

In 1948 we were able to confirm the earlier goniometric work of G. F. Herbert Smith (1906) that paratacamite and atacamite are not identical species (Max H. Hey, 1950) and showed that the two minerals give different X-ray powder patterns. This result was further extended by Clifford Frondel (1950) to a single 'crystal and thermal study of paratacamite, in the course of which he measured the rhombohedral unit-cell dimensions and showed that this mineral can be artificially produced by various methods as well as by the action of salt-water on copper.

In 1926 schultenite from Tsumeb, Otavi, South-West Africa, was described as a new mineral by L. J. Spencer and related to the compound PbHAsO4. The specimen on which the original description was based is still unique in the British Museum collection and was used for the present study. There appears to be no record in the literature that the mineral has been discovered in any other locality

For the X-ray examination rather small fragments (less than 0·1 × 0·05 mm.) were broken from pieces of crystals since all the available crystals were too large and the material has a high absorption to X-rays. Single crystal rotation, oscillation, and Weissenberg photographs in 6-cm. diameter cameras with Cu-Kα radiation as well as Laue photographs (crystal-plate distance 4 cm.) with tungsten radiation were used to derive the unit-cell dimensions and space-group.

Early in 1947 an unusual mineral deposit was discovered at Mavuzi in the Tete district of Mozambique. The discovery was made by native boys searching for corundum on behalf of Senhor Mario Canuto de Carvalho, a Goanese prospector who had for some years been associated with primitive gold and corundum operations on the north bank of the Zambesi. The dominant ore-mineral in the new deposit was superficially similar to the pegmatitic samarskite found in small quantities in the mica-mining districts of the Alto Ligonha in eastern Mozambique; and when exposure of the mineral to a photographic plate confirmed that it was radioactive, the identification as samarskite was accepted both by local prospectors and by most of the field geologists who later worked on the deposits. The presence of uranium in the ore was first proven in a chemical analysis by the Southern Rhodesian Geological Survey.

Pargas in Finland and MansjSand and Tennberg in Sweden are the only three Fennoscandian contact metamorphic limestone occurrences of which systematic accounts have been published; in the first case by A. Laitakari (1) and in the two latter ones by the present author (2, 3). A more complete analytical programme would have been desirable, and unfortunately many of the analyses are incomplete, especially as regards the determination of the valency of the iron. Nevertheless, the available data, and a few I have been able to add later, may suffice to give us a general idea of the paragenetical and chemical differences between these Archaean mineral parageneses and those of much younger age which occur in connexion with the limestone masses associated with the alkaline occurrence of Alnö in Sweden.

A fundamental problem arising out of the study of symmetrical point groups can be formulated as follows: Let N points in threedimensional space be connected two and two in every possible way by straight lines: what relations must exist between the lengths of these lines if the points are equivalent members of a symmetrical point group ?

The methods of projection used in crystallography (e.g. the stereographic projection) at once show that the points may be considered to be the images of straight lines or planes. The problem formulated above has therefore a direct application to descriptive crystallography and can in this connexion be stated as follows:

A complex of N planes is determined by the points of intersection of the normals with the surface of a unit sphere, i.e. by their poles. What now must the angular relations between the planes be if all are equivalent, that is to say, belong to one and the same simple form ?

Les chlorites peuvent être définis d'après G. Tschermak (I), puis t A. Lacroix (2), comme des silicates hydratés d' Al, de Mg, et de Fe, de couleur généralement verte, possédant un elivage facile suivant (001), les lames de clivages étant flexibles, sans être élastiques, comme celles du mica. Dans un travail antérieur, l'un de nous (3) avait tenté d'établir une classification de ces minéraux, en se basant directement sat les données de l'analyse chimique, sans faire intervenir d'idée théorique sur leur constitution, comme l'avait fait G. Tschermak et d'autres auteurs aprés lui. Peu de temps après, un certain nombre de recherches, effectuées à l'aide de rayons X, ont permis d'élucider les caractéres essentiels de la structure de ces phyllites. On peut done raisonnablement en tenter une nouvelle classification chimique tenant compte du schéma structural établi actuellement. C'cst ce que nous nous proposons de faire dans ce mémoire, aprés avoir exposé quelques remarques sur des travaux récents.

Paralaurionite from a new locality, the Mammoth mine, Arizona, is described. X-ray study and chemical analysis confirm the original characteristics of the mineral as described in 1899 by G. F. Herbert Smith. Measurements are given which establish new forms on crystals from Arizona and also on crystals from a South American locality. A complete angle table for twenty-eight forms is presented.

In his long conduct of the Mineralogical Magazine and Mineralogical Abstracts our Editor has always shown a ready interest and understanding for each new phase of mineralogy as it has appeared, and thus a contribution to any part of the wider realm of mineralogy would fall in the range of Dr. Spencer's comprehending appraisal. At the same time Dr. Spencer's own published work in mineralogy and the style of his abstracts of the works of others show that his personal interests incline to the classical natural history aspect of mineralogy, which gives first importance to exact observations that establish the individuality of new species, improve and extend the knowledge of well-defined species, or disprove the existence of supposed new minerals.

The peninsula in which the mainland of Shetland ends north of Ronas Voe and Colla Firth is occupied mainly by the Ronas Hill Granite. This body is intrusive into a metamorphic series consisting of orthogneiss on the north and paragneiss oil the north-east, east, and south-east of tile peninsula. It is a biotite-granophyre within which earlier bodies of basic rock varying from diorite to gabbro are found. It is unsheared and unfoliated and is cut by a swarm of dikes with north-south trend which extends from tile north coast to Ronas Voe. There is evidence also of the existence of dikes earlier than the granite. The later dikes comprise spessartine, microdiorite, porphyrite, quartzfelspar- porphyry, and a great variety of felsites which are generally granophyric and spherulitic. Many of the felsites contain riebeckite and aegirine and have a corresponding blue or blue-green colour. From observation of chilling of dike against dike and intersection of dike by dike it has been found that tile basic dikes, spessartine, microdiorite, and porphyrite, are the oldest of the suite, the quartz-felspar-porphyries are older than the felsites, and the blue riebeckite-felsites are younger than white, pink, and dull red felsites which contain neither aegirine nor riebeckite

In vielen Lehrbüchern der Erzlagerstättenkunde und Mineralogie werden die eigentümlichen Vorkommen von Fe-führendem gediegen Nickel als Musterbeispiele orthomagmatischer Differentiate ange-sprochen. Daß das bisher, soweit mir bekannt, unwidersprochen geschah, hat verschiedene Gründe:

1) paßt die Durchschnittszusammensetzung Ni66 Fe33 bis Ni75 Fe25 leidlich gut mit der Lage des Schmelzpunktsminimums im binären system Ni—Fe

2) stammen die wenigen in situ gefundenen und die recht zahlreichen aus Flußseifen ausgewaschenen Stücke eindeutig aus Serpentinen oder Peridotiten, wodurch ein Vergleich mit den Vorkommen gediegenen Platins in Dunit oder Chromitit nahelag

3) hat das chemisch immerhin unedel Verhalten des Ni und natürlich erst recht, des Fe einen Zweifel an der so etwas als deus ex machina wirkenden ‘orthomagmatischen’ Natur garnicht aufkommen lassen und

4) schließlich war das Material in allen Sammlungen so spärlich und wert voll, daß man sich nicht recht an eine ohne größeren Material­verbrauch nun einmal nicht mögliche Untersuchung getraute und so auch die Zahl der Analysen klein und in der Auswahl des Stoffes — zufälligerweise — unglücklich war. Es wird im Folgenden erkennhar sein, wie wenig stichhaltig die Gründe 1-3 sind und daß jede et was umfassendere Untersuchung sofort ‘magmatische Ausscheidung’ oder gar ‘liquides Entmischungsegregat’ ausgeschlossen hätte.

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.

The high-silica sericites generally contain a corresponding appreciable quantity of a divalent element, usually magnesium, and their chemical composition is interpreted as being intermediate between that of muscovite, KAl2 (AlSi3)O10(OH)2, and that of the equivalent high-silica mica leucophyllite, KAlMg (Si4)O10(OH)2. The series muscovite-leucophyllite includes the named micas phengite (high-silica sericite), mariposite, and alurgite. Selected analyses are plotted and fall on a corresponding straight compositional variation line from muscovite to leucophyllite. It is shown diagrammatically that the analysed sample of mariposite probably contained about 8 % of quartz. It is recommended that the only species names in this series to be retained are those of the end members muscovite and leucophyllite. Their indices of refraction and specific gravities are very similar.

In earlier analytical work on stony meteorites the analytical results were given in a number of different ways. Not only the principles, but also the methods used in the calculation of the mineral composition as derived from the chemical analyses, were of a different kind in almost every description of a stony meteorite. The same remarks of course apply to a certain extent also to the older descriptions of terrestrial rocks. The publications on the 'Quantitative [(American) system of[ classification of igneous rocks' (1) and some publications by Henry S. Washington, especially a paper on 'The statement of analytical results of rock analyses' (2), contributed greatly to the unifying of the methods of representing the results of chemical analyses of rocks and calculating their mineral composition. Later on other systems for the statement and calculation of rock analyses have been introduced by other petrologists, especially by Paul Niggli, and all this work, taken together, has greatly contributed to clarification of the different ways in which the results of rock analyses can be stated and made use of in the petrological study of rocks.

The study of minerals, using X-ray goniomcters in place of optical I instruments, has proceeded far in recent years. It is now a common practice among mineralogists and petrologists to confirm the nature of a given specimen by X-ray methods when there is some doubt about the identification by the older methods. The occurrence of pseudomorphs sometimes leads to misidentifications even in crystals of large size. If the material is cryptoerystalline it may be almost impossible to make an identification by optical methods. In such cases X-ray photographs may be of great assistance.