The labour of tracing the history of the Red Silver Ores, of collating the literature, and of tabulating the crystalline forms previously observed, has been, to a large extent, rendered unnecessary by the memoir published by E. Rethwisch (Neues Jahrbuch für Mineraloqie, Beilage Band iv. (1886), pp. 31-109), under the title "Beiträge zur mineralogischen und chemischen Kenntniss des Rothgültigerzes."

Some time ago a specimen studded with small but well developed crystals of a sky-blue mineral, supposed to be percylite, was offered for the British Museum collection : the rarity of percylite and the excellence of the crystals on this specimen rendered a careful examination desirable. The specimen had been obtained from the Mina Beatriz, Sierra Gorda : on a large-scale chart, kindly placed at my service some years ago by Mr. George Hicks, of Newquay, Cornwall, Sierra Gorda is shown situate between the Bay of Mejillones and Caracoles, about 20 or 30 miles from the latter; longitude 69°29' W. of Greenwich, latitude 22°55' S. : at the truce of 1884 possession of this district was temporarily assigned to Chili.

A mineral from New Zealand, said to be chromic iron, presumably from its occurrence with serpentine, being found to contain no chromium, was analysed under my direction by Mr. F. J. Cairns with results given below. The mineral occurs both massive and crystallised in a light yellowish-green serpentine, with which it is so intimately mixed that it was found impossible to pick a specimen for analysis that was entirely pure, though as far as possible the distinct crystals were taken. These crystals are about one-fourth of an inch in diameter, and all noticed have the form of the rhombie dodecahedron. The specific gravity is 4·67, and the colour iron-black.

The immediate object of the present paper is to place on record the history and characters of several Atacama meteorites of which no description has yet been published; but incidentally it is convenient at the same time to consider the relationship of these masses to others from the same region, which either have been already described, or at least are stated to be preserved in one or more of the known Meteorite-Collections.

As long ago as 1816, Brewster showed that many crystals have a lamellar structure developed in them by pressure, and his observations became the starting point of a long series of very valuable researches. Reuseh proposed that the planes along which such structures are developed by mechanical means should be called "Gleitflächen" (gliding-planes), and he, Pfaff, and other mineralogists have investigated a number of curious cases of the kind. Baumhauer in 1879 showed that the lamellar structure could be brought into existence, in the ease of calcite, by simply inserting s knife-blade in a definite direction into cleavage fragments of the mineral, and his observations were confirmed in the following year by Brezina.

The first volume of the Transactions of the Geological Society of Glasgow contains the following notice of Zeolites as occurring in the banks of the Rye Water:—"About one-and-a-quarter miles below Howrat Toll-bar, white and red stilbite occur, small white prehnites, with fine pellucid quartz approaching to hyalite, and calcite."

In the New Red breeciated conglomerate of the coast of South Devon there are numerous fragments of Devonian limestone, on the weathered exterior of some of which botryoidal and concentric chalcedony is commonly found. There does not seem to be anything in the nature of the material to call for a new name from a mineralogical point of view; but, as the ettalcedonic shells to be described are peculiar in their mode of occurrence and form and are locally called Beekites, and the mineral is commonly spoken of as Beekite, after Dr. Beck, Dean of Bristol, who first called attention to it, I will use the word where convenient.

Some experiments on the hydrophane recently found in Colorado led Mr. G. F. Kunz (Am. J. Sc. XXXIV. pp. 479-480, Dec. 1887) to the extraordinary conclusion that this mineral absorbed more than its own bulk of water. Mr. Kunz, with great kindness, furnished me with a supply of this variety of opal from the locality in question. I can confirm the accuracy of his experimental results, but not of his deductions therefrom.

Before describing some features of special interest in the microporphyritic quartz crystals of an Indian felsite, it may be as well to say a few words, by way of preface, regarding the rock itself.

About 85 miles to the north-west of the town of Delhi, in the peninsula of India, a hill rises abruptly from the plain to the height of 630 feet. It is one of a series of similar elevations separated from each other by some miles of sandy soil which strike the traveller with their resemblance to a group of islands in a tempestuous sea—an idea greatly favoured by the long swelling waves into which the sand is thrown by the strong westerly winds which prevail in that region during the greater part of the year.

Mynydd Mawr is a conspicuous hill with a craggy face towards the north, and a well-marked corrie (Cwm Du) on that side. It lies to the south-east of Moel Tryfan and the west of Llyn Cwellyn (Carnarvonshire). On the Geological Survey map it is represented as a somewhat rounded oblong patch of felstone, about 1⅜ mile from east to west, and a mile, or a little more, from north to south, intrusive in Lower Silurian (Ordovieian) rocks, which are probably Arenig. I passed some years since to the north of the above-named face, and collected specimens from erratics which were plentifully strewn over the lower land. On microscopic examination I found them to contain a very puzzling and remarkable mineral which I have long intended to describe, but kept deferring this in hope of being able to revisit the place to obtain more specimens for examination, and by taking these from rock in situ, to prevent any question arising as to the true source of the rock.

Through the cordial assistance and generous hospitality of Mr. Brown, of Dunipaee, formerly a member of the Mineralogical Society, I have lately been enabled to add very largely to the list of mineral localities in the Western Islands of Scotland.

I propose to add one more account to those which have already been published of this mineral. It is described as a rhombie mineral in Dana's Mineralogy and other standard works. Latterly it has been described by Reusch as an anorthic mineral, from National Belie Mine, Red Mountain, Colorado, in the Jahrbuch für Mineralogie, 1887, Bd. II. Now I describe it as monoclinic, principally from a study of that variety of it which occurs in Anglesey, of which an account was published by Dr. Percy in 1875 in his Metallurgy, Vol. "Fuel."

In a late number of the Magazine I mentioned that I had obtained from several of the Treshinish Islands specimens of gyrolite, and that one of these carried crystals which seemed sufficiently perfect for the determination of the form of the mineral.

A careful examination of the specimen showed it to be somewhat fragile; and, as we know that the mineral is itseff excessively tender as well as soft, I thought it desirable that the most should be made of so unique an example.

The locality of the specimen which is the subject of the present note is Namaqualand, South Africa. It was brought over from Africa, together with other minerals, about the year 1861, by Mr. Edgar Layard, who was at that time acting as curator of the Museum at Cape Town. It was in the same year that Mr. Layard presented to the British Museum Collection specimens of Namaqualite, the mineral which was subsequently examined by Professor Church and shown to be a new species. The connellite was given by Mr. Layard, among other specimens, to Mr. T. Davies, who in 1887 presented it to the Museum. It was not recognised as certainly connellite, but was put aside for chemical examination as being either clinoclase or connellite.

Specimens of this rock were presented a short time since to the British Museum by the Earl of St. Germans, and Mr. T. Davies, knowing my interest in pierites and peridotites, kindly requested me to examine them and communicate the results to the Mineralogical Society. The rock occurs, as I am informed, in boulders between Menheniot and St. Germans. The picrite of the Clicker Tor, near the former place, is well known and has been more than once described, but, as all specimens which I have seen from that locality are very different, macroscopically and microscopically, from those now sent to me, it may be well to put on record a description of the latter, which, after the excellent summary of the mineral character of picrites given in Mr. Teall's British Petrography, need not be lengthy.

This mineral tar, which, from its elasticity, though somewhat weak, resembles elaterite, is found at the Craig Well, near Dingwall.

It is an intensely black, lustrous, sticky substance, of the consistency of tar, and from its being associated with albertite it may be looked upon as a variety of that asphalt.

Last Easter, when I was with Professor Hughes and his geological students at Torquay, I found some very perfectly preserved pseudomorphs of hæmatite after iron pyrites. They occur in the calcareous red shale in the most northerly part of Saltern Cove, Torquay, where the unconformity of the Trias and the Devonian is well shown.

Some of the published analyses of specimens of Dufrenite have afforded results not in good accord with the chemical formula 2Fe2O3, P2O5, 3H2O, usually ascribed to that species.

Moreover, since analyses of a crystallised Dufrenite from Cornwall gave results showing a higher ratio of acid to base than demanded by the above formula, a re-examination of the ordinary botryoidal variety of the mineral seemed desirable.

The mechanical inclusion of foreign substances in crystals during their formation is of such common occurrence that it might appear superfluous to record further examples, were it not that the present ease is a somewhat unique one. All mineralogists are acquainted with the inclusion of sand and clay in selenite, celestite, and calcite, of which the Fontainebleau limestone is a striking example. Delesse found the crystals of calcite from that locality to contain 57 per cent. of sand, and to have a sp. gr. of 2·84, whilst the sp. gr. of pure calcite is given by Beudant as 2·721 to 2·723, which demonstrates that the inclusion of the heavier quartz grains raises the sp. gr. of the impure crystals.

Several years ago Dr. Thomas Aitken, of Inverness, put into my hands a mineral which he thought to be new, with the request that I would analyse it.

He stated that the mineral occurred in veins in the conglomerate of the Old Red Sandstone, near Loch Bhruithaich, in Inverness-shire ; that it had been found by and given to him by the head gamekeeper on the Lovat property, and that similar pieces had been given to Mr. Wallace.

The specimens which he put in my hands, and others which he showed me, consisted of one side of a vein-plug, and were formed of alternate bands of foliated flesh-coloured baryte, with narrower ones of the substance in question.