In the account of an investigation of the optical properties of gypsum published by one of us (A. E. H. T.) in 1908 it was stated, as the result of direct measurement in sodium-light of the optic axial angle of a section-plate perpendicular to the first median line, which was heated in an air-bath, that the substance became uniaxial at 105.2° C. Three other section-plates examined subsequently gave somewhat higher values, the results ranging from 109.5° to 114.2° C. These figures were arrived at after a considerable correction, amounting to as much as 7°, had been applied for conduction along the crystal-holder, the temperatures actually observed being greater by this amount.

For the first of the three minerals to be described in the following pages we are indebted to Mr. W. G. Fearnsides, who collected it in North Wales in the autumn of 1908, and we desire to express our best thanks to him for the readiness with which he placed at our disposal enough suitable material for a complete analysis. The other two minerals were collected by ourselves.

An occurrence of the rare mineral dundasite (hydrous carbonate of lead and aluminium) at the Welsh Foxdale mine, Trefriw, Carnarvonshire, was described by Dr. G. T. Prior in 1906. Since then the mineral has been found by the writer at two additional localities in the United Kingdom. Certain specimens collected in 1910 at the well-known Mill Close mine, Wensley, Derbyshire, show a mineral which examination has proved to be dundasite. It occurs here as minute white or yellow spheres, not exceeding ¾ mm. in diameter, the exterior smooth and waxy, the interior radiating and silky.

According to the accounts which have been published by members of the Egyptian Geological Survey, a number of meteoric stones fell to earth on June 28, 1911, at about 9 in the morning, in the hamlets to the west and north of the village of El Nakhla El Baharia (31° 19′ N., 30° 21′ E.) in the district of Abu Hommos, about twenty-four miles east of Alexandria, Egypt.

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.

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.

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.

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.

In a recent number of the Mineralogical Magazine an analysis of strüverite found in perak was published. This mineral was submitted to me by Mr. R. L. Corbett for examination in August, 1909, and as I failed to detect its relation to the Piedmont strüverite described shortly before, the material was forwarded to the Imperial Institute in accordance with an arrangement between the Institute and the Federated Malay States Government. While waiting for the results of the analysis, the locality from which the mineral came was traced and some prospecting work carried out to ascertain the amount of material available. This work afforded information that is of interest concerning the origin of the mineral.