This occurrence of barytes is somewhat remarkable and interesting from several aspects :—The peculiar conditions under which it seems to have been deposited, the limited quantity, and the perfection and richness of the crystallographic development.

It was found some two years ago in one of the shale pits of the Young's Paraffin oil Company, and my friend Mr. J. S. Thomson, to whom I am indebted for two of the four or five existing specimens (of which one, I am happy to say, has been deposited in the Museum of Edinburgh), was so kind as to procure for me from the Mining Engineer of the Company a sketch of the Geological Strata of the neighbourhood, in which the position of the beds containing the crystals is indicated (Plate II.).

The three varieties of apatite at present known to occur in Cornwall are the sea-green limpid crystals from St. Michael's Mount and other places, the dirty-white, semi-opaque, hexagonal prisms associated with axinite from Botallack Head, and the thin hexagonal plates, described and analysed by Prof. Maskelyne and Dr. Flight as coming from a new locality, now known, however, to have been obtained by the late Mr. Tailing from Fowey Consols, and previously noted from this mine by Greg and Lettsom. To these must now be added a new variety which was lately brought to me as chalybite from the deep workings of Levant Mine, St. Just. The specimens are closely analogous to those analysed by Dr. Flight, but differ slightly in chemical composition and mode of occurrence.

The three varieties of apatite at present known to occur in Cornwall are the sea-green limpid crystals from St. Michael's Mount and other places, the dirty-white, semi-opaque, hexagonal prisms associated with axinite from Botallack Head, and the thin hexagonal plates, described and analysed by Prof. Maskelyne and Dr. Flight as coming from a new locality, now known, however, to have been obtained by the late Mr. Tailing from Fowey Consols, and previously noted from this mine by Greg and Lettsom. To these must now be added a new variety which was lately brought to me as chalybite from the deep workings of Levant Mine, St. Just. The specimens are closely analogous to those analysed by Dr. Flight, but differ slightly in chemical composition and mode of occurrence.

These crystals of anglesite were given to me by Dr. Gadow, the Strickland Curator to the University of Cambridge, who obtained them while on a zoological expedition to Portugal.

They were given to him by the agents at the San Domingos copper mines near the Guadiana river in the province of Algarve, South Portugal, as crystals strange and unknown to them.

The only Portuguese localities recorded at present for anglesite are far north of these mines.

The San Domingos mines are worked in a portion of the great metallic lode or bed which stretches from the S.W. of Portugal, across the southern portion of Spain, in the province of Huelva, in an E.S.E. direction, and appearing again in a similar manner and direction on the other side of the Mediterranean in Algeria. The age of the surrounding strata is a matter of dispute.

This mineral, lead dioxide, does not seem to have been examined since it was first noticed by Breithaupt and Plattner in 1837 (Journ. pr. Chem. x. 508). This specimen, named "Schwerbleierz," is said to be probably from Leadhills, and the mineral is called, in the manuals of Dana and others, a doubtful species. It was named Plattnerite by Haidinger and subsequent authors.

A short time ago my friend Mr. Thos. Davies, F.G.S., of the British Museum, asked me to analyse a mineral from Leadhills, Lanarkshire, which he had had in his possession for some years, but the examination of which he had, from various causes, frequently postponed. On examination it was found to be lead dioxide—Plattnerite.

Some two years since the authors received from East Cornwall examples of a erystallised mineral presenting features dissimilar to those of any species previously known to them, but presumably referable to Dufrenite. The specimens obtained were from the central part of a narrow neck of "dead ground" (compact ferruginous quartz rock) connecting the much broader E. and W. continuations of a lode, yielding respectively copper and tin ores.

The freshest crystals have a vitreous lustre, and vary in colour from almost black to a light apple-green, their sections, however, being of a yellow brown to yellow. Where, as commonly, some superficial chemical change has taken place—seemingly into limonite—the colour is from red to brown or yellowish brown.

The tin from the Straits Settlements has hitherto been solely derived from the alluvial deposits, and is consequently in the form of alluvial or "stream" tin—each grain of Cassiterite being separate, and in many cases so considerably water-worn as to afford evidence of its having been washed down for a considerable distance; the angles of the grains having given place to smooth surfaces during their deposition.

The largest grains occur on the tops of some of the hills, with a diminution in size noticeable with distance from the hills.

During the course of an inquiry into the nature and extent of the less known iron ore deposits of Scotland undertaken in connection with a paper to be communicated to the Society of Antiquaries of Scotland during the Winter Session 1886-87, I have been led to consieler certain masses of Bog Iron Ore which are distributed somewhat widely over the less cultivated portions of the country. The present communication deals only with the north-westerly portion of Ross-shire, and most of the localities are within the parish of Gairloch.

In my previous communication I drew attention to an impure variety of Agalmatolite found on Creag Mhôr Thollie, and which contained an excess of silica. A similar body was referred to in connection with Mr. Hamilton Bell's paper on "New Localities for Agalmatolite" as having been obtained from Ballater Pass. In connection with the material obtained at Creag Mhôr Thollie, I expressed the opinion that the agalmatolitie mineral had been formed in the presence of an excess of silica which had become combined with the other ingredients, forming what I then termed a "Siliceous Agalmatolite."

During the past summer I have again had an opportunity of examining the Creag, and towards the northmost end found very large masses of the pure mineral.

The mineral to which this notice refers is obtained from New Jersey. It is very largely employed for paper-making in place of China clay (Kaolin), and gives, amongst other advantages, a much more pure effluent, fully ninety per cent. being retained in the paper. From its fibrous nature it appears to attach itself to the smaller paper particles and retain these also. The very high and beautifully smooth glaze of the American papers is largely due to the use of this substance.

The mineral is of a highly fibrous character, almost pure white, perfectly insoluble in water, is greasy to the touch, and readily broken down in the fingers.

Prof. Tennant, of London, and I, identified the two "Albertites " in 1862. I was then a Commissioner for Nova Scotia at the Great Exhibition. In the ncighbouring Court of New Brunswick there was a tub full of specimens of Albertite, which were freely given to visitors by Mr. Daniel, the Commissioner for New Brunswick, and myself.

It was, therefore, no astonishment when the Professor's assistant put into my hand a piece of "Albertite" as I entered the shop, and asked me what I thought of it. I said, "It is a piece of our New Brunswick Albertite." He replied, it was not from New Brunswick, but from some part of England, and showed me a boxfull that had just been received. The only guide to the locality whence it came were the markings on the lid of the box—" Aberdeen Railway" and Kiltearn.

Certain specimens of rock lately obtained by me from the "Single Rose" Clay Work, near St. Austell, Cornwall, examples of which are now submitted to the Society, illustrate well the processes by which, in some instances at least, granite has been transformed into an aggregate of quartz and schorl.

A comparison of the chemical composition of orthoclase from Roche with that of kaolin from the neighbouring district of St. Stephen's shows that in the passage of felspar into China clay there is approximately a loss of 26 per cent. SiO2 and a gain of 19 per cent. Al2O3 and 12 per cent. H2O.

In the case of many common rock-forming minerals—the felspars, the pyroxenes, the olivines and the micas—it has been shown that the crystals which have existed in rock-masses at great depths exhibit constant and characteristic differences from the crystals of the same mineral, in rocks of identical composition, which have been formed at the surface. It has been proved, moreover, that these differences become mere and more pronounced in proportion to the distance from the surface at which these rocks have originally existed.

Although some of these peculiarities of the crystals of deep-seated rockmasses can be satisfactorily accounted for by the conditions of pressure and slow growth under which they were originally formed, yet there are others—and these by no means the least striking of them, such as the continuous bands of fluid-enclosures, the avanturine structure and schiller, and the chatoyant phenomena—which are clearly not original, but are due to secondary actions.