To the geologist, the mineralogist and the chemist, two of the observations made during the voyage of the Challenger are of especial interest. One of these observations is the occurrence over vast areas of the deep sea bottom of a peculiar red clay, containing silica, peroxide of iron, and alumina. The other discovery to which I refer has been described by Sir Wyville Thomson as the occurrence throughout this red clay of nodules of “nearly pure peroxide of manganese.” To these nodules, as well us to the red clay, an organic origin has been assigned. But the immediate source of so much manganese is hard to find, for this element is by no means an abundant constituent of animal or vegetable organisms. The difficulty is, however, somewhat lessened when the manganese nodules are submitted to a more minute chemical examination. From two correspondents I have received an ample supply of these curious concretions, accompanied by a suggestion that they should be submitted to chemical analysis.

Whilst detaching a small crystal of leadhillite for examination with the polariseope, from a specimen brought from the Leadhills, Lanarkshire, which came into my possession some years ago, I observed one side of the mass to be more or less encrusted with a thin drusy coating, which, from its hardness and streak, I was led to suspect might be either the above species, or Laxmannite, described in 1868 by Nordenskiöld in the Journ. f. prakt, chem. of that year.

The bulk of the specimen consists of massive greenish pyromorphito mingled with cerussite, upon this occurs the vauquelinite. The remaining minerals are lanarkite, leadhillite, caledonite in tufts of minute acicular crystals, massive black eerussite and quartz.

This mineral was first observed by Mr. C. E. Wilkinson, the Government Geologist, and obtained by him from a cutting on the Bathurst Road, near the Cox River.

It occurs as small irregular veins, of a pleasing salmon eolour, running through a soft bluish grey shale, the veins together with the included plates of shale are sometimes six inches thick, but usually smaller; the actual veins of the mineral itself being only about one eighth of an inch thick. Some difficulty was on this account experienced in obtaining sufficient of the sample pure enough for analysis.

The mineral appears to be partially crystallized, nothing definite could be made out, but some of the confused crystals had somewhat the appearance of rhombic prisms. It apparently cleaves parallel to the long axis, and lies perfectly at right angles to it.

It often happens in mineralogical inquiries that from scarcity of materials, lack of time, or other causes, the important datum of specific gravity is not secured. Now, however, that Sonstadt has shown us how to prepare a nearly colourless and perfectly transparent liquid with a density three times as great as that of water, there will generally be no difficulty in ascertaining the specific gravity of very many rare minerals as to which our knowledge remains imperfect. More than this, two minerals if of different specific gravities (provided one is less than S.G. 3.0), may often be easily separated from one another if they are in fragments of appreciable size. Thus, pieces of quartz with a S.G. of 2.655 float, while fragments of beryl (S.G. 2.691) sink in a solution having S.G.=2.67. A very simple apparatus is required for the purpose. (See fig. 7, Plate. VIII.)

At Terras mine there is an interesting junction of a well-marked tin-bearing elvan, whose course is about north and south, with a bed of greenstone, whose general bearing is nearly east and west. Near the junction, a few years since, a shaft was sunk 40 fathoms deep for the purpose of working a tin lode which was believed to cross the elvan just refered to at that point. At a depth of about 10 fathoms the bed of greenstone was met with, and it continued for 6 fathoms in depth in a very hard state, but from thence to the bottom of shaft it was much softer.

The rock is one of the hardest and toughest I have ever come across. Ordinarily it is composed of a fine-grained mixture of hornblende and silica, but it contains numerous narrow cavities or partial fissures, which near the shaft in question are often studded over or lined with small crystals of the three arseniates mentioned above.

There are found scattered up and down our Mineralogical and other literature, a great many names of Minerals which do not appear to have been satisfactorily determined, or of which very little is actually known.

Many of these minerals have been called Doubtful. The following list, I hope, will be inserted in the Magazine, so that the members of the Mineralogical Society and others interested may be able to supply more definite information concerning them.

Obviously, it is not my object to impugn the general accuracy of any of the authorities appearing in this long list; but the accumulation of the most reliable mineralogical data attainable, and the focusiug of it, so to speak, where it may be seen by anybody interested.

At the foot of the terminal and almost inaccessible cliff of the hill—name unknown—which towers immediately to the south west of the harbour of Waii or Hoiwig, in Bordöe, Faröe, the writer obtained the specimen—a single one—of which the following is an analysis:

The island of Bordöe, like the most of Faröe, is built up of strata of bedded trap with mural cliffs, which alternate with terraces of grass clad debris. At this part of the island, the terraced trap consists of a wackenitic “claystone,” which is very friable, light in colour, easily disintegrated, and in places tufaceous in aspect. Its amygdaloidal druses are very few and far between.

Under the name of Romeite a mineral from Borneo has found its way into many collections. There is, however, little in common between the true romeite of St. Marcel in Piedmont and the so-called romeite of Borneo. Both are hyacinth or honey-yellow with darker portions verging towards clove-brown; both contain antimony ; here all resemblance ends. The easy solubility in acids, and the low specific gravity (under 2.0) of the Borneo mineral at once separate it from romeite; it is, in fact, nothing but a variety of allophane containing a little antimonious oxide. The following analysis may not be without interest; the mineral was selected and purified by mechanical means as far as possible, but still contained a small quantity of gangue, chiefly insoluble silica.

In the autumn of 1871 I found in a large cavity or “vugh” in the schorlaceous granite of Boscaswell Downs, in the parish of St. Just, Cornwall, a number of black and opaque hexagonal prisms, having ragged terminations, which I at first took to be pseudomorpbs of black tourmaline (schorl), after quartz. They were set aside for further examination and forgotten until the beginning of the present year, when I undertook their examination.

I found that, although they were very compact, the sp. gr. was only 2.747, which at once negatived the idea of schorl, the sp. gr. of which ranges from 3.0 to 3.3. I then cut a number of sections for microscopic examination, and these at once shewed that the prisms were composed of clear and eolourless quartz, containing an immense number of tourmaline crystals, mostly very thin and arranged in feathery groups as in Plate III, figs. 1 to 4.

As black tourmaline or “schorl” is one of the most abundant and widely distributed of the minerals of the West of England, it is perhaps somewhat remarkable that the variously colored and colorless varieties are extremely rare both in Cornwa]l and Devon. Among recorded localities, I am not aware that the green or brownish green Zeuxite has occurred, except at Huel Unity, Carn Marth, and Great Work Mine, in Cornwall, and near Okehampton in Devon, while the colorless variety Achroite has only been observed at Roscommon Cliffs, in St. Just; and the red, blue, and yellow varieties are so far quite unknown in the two western counties. I have lately been examining a number of specimens obtained in a large open tin working at Rock Hill, in the parish of St. Austell, Cornwall, in 1871 and 1872, and among them I have found several specimens of Achroite. When I first obtained them I thought they were quartz, and, indeed, I referred to them as such in a paper which I read to the Miners’ Association of Cornwall and Devon, in 1872, but I am now satisfied that they are colorless tourmaline or kchroite.

These constitute interesting objects for the microscope. The first mentioned is calc spar, having perfect rhombohedral cleavage; it is transparent, or translucent, apparently coloured topaz yellow or mnber, by the intimate diffusion of oohreous iron throughout. The distribution of the colouring iron oxide through the carbonate of lime is minutely microscopic, in tangled interlacing curved lines, many of which, if not all of them, are hollow tubes not unlike maccaroni or vermicelli, but, although this form of iron oxide is distributed through the calc spar in such close masses, it does not seem to affect the cleavage planes of the latter, which separate as readily as if no ochreous iron had been present.

One of the blast furnaces at the the Eglinton Iron Works, Kilwinning, having been blown out, it was noticed that on the hearth there was a curious deposit of a bluish black semi-metallic colour, which by its brittleness seemed to be a slag. Mr. Smith having forwarded to my friend Mr. John Young, F.G.S, a sample of the substance, it was submitted to me for analysis and examination. On a cursory examination it was seen that it was not homogeneous but consisted of different substances mixed, the most conspicuous being the bluish substance with a plumbago lustre before referred to. On powdering it the substance was round to contain pieces of metallic iron in irregular masses inbedded in the matrix.

This Lamp is shewn half size in figs. 1 to 4. Fig. 1 is a section of the whole lamp ; fig. 2 a view from above ; fig. 3 shews the mode of folding the wick ; and fig. 4 the tinplate cover, which serves as a stand while the lamp is in use.

It is provided with a “bayonet” slot, which works over the little pin shewn in fig. 1, so as to keep the cover in place when it is put on over the lamp.

The body of the lamp is made from a piece of iron or lead gas pipe, 1 1/2in. internal diameter, to one side of which the wick holder is soldered. I find that “night light” grease suits admirably—ordinary composite candies do very well.

Since my communication on this subject published in the first number of the Mineralogical Magazine, I have made further observations, and have found other specimens greatly varying, but all embodying the same general principle of solid quartz enclosing the oxides of iron.

The quartz is perfectly solid, breaking with its usual eonchoidal fracture, and though richly colored with the oxides of iron disseminated through it in beautiful forms, is itself transparent, so that the forms and colors of the iron are well seen. The colors are various shades of red, yellow, amber, grey, &c., and [hose colors are distributed in well-defined forms, and not in mere tints as in the case of amethyst, &c.

From a very early period gold has been found and worked for in Scotland. We have records dating as far back as the time of James I., in which grants were made to different parties to search and mine for this metal; and no doubt it was obtained at a much earlier period. The gold ornaments found in Scotland, with other relies of pre-historie times, were doubtless manufactured from native gold. Several localities are mentioned in these old grants where gold was to be searched for; but by far the most important district is that generally mentioned as Crawford Moor, which appears to include the range of hills at Wanloekhead and Leadhills, and the streams which fall into the Clyde on the one side, and those which reach the Nith and Annan on the other. The head water of the Tweed, where gold has been found to a limited extent, appears to have been included in this district.