Some time previous to 1894 the late Sir Henry A. Miers, then an assistant in the Mineral Department of the British Museum, collected together all the books in the departmental library which gave a systematic account of the minerals of particular regions. Since then the set has been considerably added to, and it now forms a very valuable, probably unique, series. Its primary use was for the more precise labelling of the localities of specimens in the collection; and as it grew it became more and more useful for answering inquiries on the minerals of particular districts. In 1900 I started a note-book for collecting further references from the literature. This was added to by the late Mr. George Savigar, clerk in charge of the departmental library; and later Miss J. M. Sweet compiled a card-index of all the entries. The department also has card-indexes of the localities of mineral and rock specimens in the collection.

During the course of a detailed X-ray study of chrysotile, antigorite, and gümbelite by E. Aruja we were asked to confirm some interesting results he had obtained on heating chrysotile to various temperatures. This we were able to do and also to provide additional data which were recently referred to in a paper by A. Hargreaves and W. H. Taylor. Although we have not succeeded in providing a completely satisfactory explanation of the optical changes observed on heating chrysotile our observations for a limited range of temperatures in the neighbourhood of 1000° C. are here recorded.

In the course of examining the cores of a boring for water at Hesleden Dene, near Castle Eden, Co. Durham (no. 2 borehole), Mr. A. Fowler noticed a cream-coloured flaky mineral of talcose aspect coating joints in the Magnesian Limestone (Permian), at depths below surface of 246 to 250 feet. The rock at these depths is an impure dolomite mudstone (Geological Survey Slice, no. E. 21304) resembling the Marl Slate, and carrying ostracods, foraminifera, and sponge spicules. Investigation of the coatings in specimens sent in by Mr. Fowler and by Mr. W. Anderson has shown that the flaky mineral is dickite, and that it is associated with fluorite, baryte, galena, zinc-blende, pyrite, and collophane. Dr. J. Phemister had previously concluded on optical evidence that dickite might be present among the minerals of metalliferous affinities discovered in the Magnesium Limestone by Mr. Fowler.

Ganophyllite was first detected in the Benallt mine as small fibrous patches varying in colour from pale pink to brown, in the thin vein cutting ore in the Ty Canol incline from which the manganese-rich chlorite, pennantite, was described. These were identified by X-ray photographs. It had previously been found at the neighbouring Nant mine by Sir Arthur Russell in 1911.