9. MINERALOGY.

To determine with accuracy the true nature of those colouring matters which, although present in extremely minute proportions, nevertheless impart to many of our gems much of their value and their beauty, is a task which has often sorely taxed the resources of the mineralogical chemist. It is still an open question, for example, whether the green tint of the emerald is due to the chromium which the mineral contains, as originally suggested by Vauquelin, or whether it is referable to the presence of certain organic constituents detected in the emerald by M. Lewy. Towards a solution of this question a contribution has recently been published by M. J. Boussingault,* who has had at his disposal more than a couple of pounds of the amorphous emerald from the celebrated mines of Muzo, near Santa-Fé-de-Bogotà, in New Granada. In the carbonaceous schist two kinds of emerald are found-known respectively as canutillos and morallones-the former being crystallized, transparent, and of great value, while the latter are uncrystallized, less translucent, much fissured, and comparatively valueless: it was, of course, a kilo of the latter that found its way to Boussingault's laboratory. Whilst Lewy has asserted that the emerald becomes opaque and colourless by calcination, Boussingault finds that nothing of the kind takes place with the morallon: the green colour is preserved at a bright red heat, but the mineral suffers a loss of nearly 2 per cent., consisting partly of water and partly of carbon. The water is regarded as existing in a state of chemical combination, since it is not expelled below a red heat, while the carbon is probably derived from the admixture of small particles of the schist in which the mineral occurs, and from which not even the finest crystals are altogether free. On the whole, Boussingault agrees with Wöhler, G. Rose, and Vauquelin, in attributing the colour of the emerald to the presence of oxide of chromium.

It is now several years since Tschermak first enunciated his celebrated theory on the constitution of the felspars, in which he showed that the several species may be regarded as isomorphous mixtures of the two extreme types-albite and anorthite. Some difficulty has lately arisen through Vom Rath's analysis of a Norwegian felspar, regarded as Labradorite, whose composition did not fit in with the theory. Tschermak thereupon called the analysis in question, and asserted that no labradorite could exist free from soda. This proposition has called forth some ingenious observations on isomorphism by Dr. Kenngott.†

* "Analyse de l'Emeraude Morallon des Mines de Muso, Nouvelle-Grenade.”— 'Annales de Chimie et de Physique,' 1870, p. 328.

"Ueber den Isomorphismus verschieden zusammengesetzter Körper.”— 'Journ. f. prakt. Chemie,' 1870, p. 77.

=

Kenngott assumes that two minerals are strictly isomorphous if the ratio between the number of atoms of metal and of oxygen is the same in the two compounds. Now, albite and anorthite may both be reduced to the general formula: 4 RO. 6 RO, where the ratio of R:0 10:16. For our author takes the liberty of writing the formula of albite in this fashion: (Na2O, A1,0 ̧) (6 SiO2); and that of anorthite in this wise: 2 (CaO. AlO) (2 SiO2. Al02). Extending this mode of formulating the silicates, he shows the possibility of the existence of a compound containing CaO.SiO2 + ALO.2 SiO2, for such an expression may be thrown into the form (CaO.AlO) (3 SiO,. AlO), which is now referable to the general type 2 RO.4 SiO2. Such a compound would be, as Tschermak observes, a labradorite free from soda, but we see at once that it is not isomorphous with albite. We forbear to follow Kenngott's interesting suggestions farther, as they lead across the border-land' of chemistry.

29

In the third number of the new Italian Geological Journala journal which we welcome as a fair sign of scientific progress in Italy-Professor Bechi publishes some analyses of minerals from Sig. Foresi's collection.* His examination of some fine limped crystals of beryl from the isle of Elba, show that they are remarkable for containing cæsium, and for holding more alumina and less glucina than other beryls. Traces of lithium were also detected by the spectroscope. A black tourmaline from the granite of the isle of Giglio-an islet rising from the waters of the Tuscan Seahas also been analysed; and for the sake of economizing space we place the composition of the two minerals side by side:

Two substances physically distinct, but occurring together near Brevig in Norway, have hitherto been confounded under the general name of Esmarkite. One of these is a true Praseolite, but the other is an extremely rare mineral, which has received Des Cloiseaux's attention during his visit to Norway. This acute crystallographer has carefully examined authentic specimens of the true Esmarkite, and pronounces it to be merely a laminar variety of the felsparanorthite.

Several new species recently described demand a cursory notice. Glaucopyrite is Professor Sandberger's name for a new mineral, obtained from Guadalcanal in Spain, and consisting of an arseniosulphide of iron, in which part of the iron is replaced by cobalt and

"Analisi chimiche di alcuni minerali delle isole del mare toscano."'Bollettino del R. Comitato geologico d'Italia,' 1870, p. 82.

Ann. d. Chim. et de Phys.,' 1870, p. 176.

copper, while part of the arsenic gives place to antimony.* Herr Boricky describes, under the name of Zepharovichite, a new species allied to Wavellite occurring in the sandstone of Trenic in Bohemia.† Tschermak proposes the name of Simonyite for a salt lately found at Hallstadt, closely related to Bloedite, from which it differs, however, in being stable when exposed to the air. Finally, Dr. Schrauf applies the name Simlaite to a mineral from Simla in India, similar to meerschaum, but containing alumina, and belonging to the group of halloysites.§

Two Cornish minerals have lately been analyzed by Professor Church-the one a variety of kaolin, akin to lithomarge, and termed Restormelite; the other is the beautiful green mineral known as chalcophyllite, or copper-mica. The formula of restormelite may be written AlO3.2 SiO +2 aq.; while the composition of the chalcophyllite may be thus expressed: 8 CuO. Al2O3. As0, +24 aq.

2

Attention is directed by Mr. S. G. Perceval ¶ to the occurrence of topazes in the granite of Lundy Island, somewhat similar to the well-known crystals from the granite of the Mourne mountains. The writer of this Chronicle has for several years past been familiar with specimens of both topaz and beryl from Lundy.

Professor How follows up his 'Contributions to the Mineralogy of Nova Scotia' by further notices of the two species-natroborocalcite and silicoborocalcite, now better known under Dana's names of Ulexite and Howlite.** Both minerals have been found good substitutes for borax in welding.

We learn from the Levant Herald' that a large meteorite fell at Mourzouk, in Fezzan, on or about the 25th December, 1869. The fall occasioned considerable consternation to a group of Arabs who were standing near, and they immediately discharged their muskets on the unwelcome stranger.tt

It seems likely that the Australian mineral lately introduced under the name of Wollongongite will in future be known by some more appropriate designation. The Rev. W. B. Clarke has pointed out that some little error has arisen in assigning to this species a local habitation and a name. In fact, the so-called Wollongongite occurs not in Illawarra, but at a place called Petrolia, formerly known as Reedy Creek, where it was recognized by Count Strzelecki as far back as 1839. Under these circumstances the name ceases to be appropriate, so that "there can be no question, I think," says Mr. Clarke, "that Wollongongite is a misnomer, and that Professor Silliman will change it."

A good deal of common sense characterizes the little minera* Jahrbuch f. Mineralogie,' 1870, p. 196. 'Sitzber. d. Kais. Acad. d. Wiss., 1869. No. XXV.

† Ibid., p. 229.

'Corr. Blatt. d. z. Mineralog.' V. in Regeusburg, 1870. p. 64.

Chemical News,' May 13, 1870, p. 223. ¶ Geolog. Mag.,' 1870, p. 192. tt Nature,' vol. i., p. 538.

** Phil. Mag.,' April, 1870, p. 275.

logical guide which Dr. A. M. Thomson has published in Sydney,* for the assistance of explorers seeking to develop the mineral resources of the colony. Plain directions are given for easily recognizing the more important species-a task at all times extremely embarrassing to the unassisted beginner.

10. MINING AND METALLURGY.

MINING,

THE newly drafted Bill amalgamating the Mines Regulation Bill and the Metalliferous Mines Bill has been printed. We cannot but think that this amalgamation will be found to be unfortunate. Nearly all the conditions of a coal mine and a copper or tin mine are so different, that it is quite impossible to apply the same legislation to them with any hope of advantage. This is shown on the face of the Bill itself. It now comprehends three sets of General Rules: one applicable to all mines; the second, to coal mines only; and the third, to mines other than coal mines. The redrafted Bill is supposed to embody the suggestions of the representatives of all the interests affected-it is therefore probably now in that form which will become law. In the last Quarterly Journal we sufficiently entered upon the principles of the Mines Regulation Bill, and therefore we need not occupy valuable space by enlarging upon its clauses.

Tin mining has, once again, resumed its condition of high prosperity in our western counties; the prices of tin ore (black tin), which have varied during the past quarter from 757. to 851. the ton, being such as to leave a large profit to the miner. The result of this is that numerous new tin mines are being opened, and the miners have full employment and are getting good wages.

Copper mining is not in the same favourable condition. The Clifford Amalgamated Mines, which employed a short time since upwards of a thousand persons, are about to be abandoned, after a long and profitable career. These mines-which comprehend the United Mines, the Gwennap Consolidated Mines and Wheal Clifford -were the most extensive copper mines in this country. The levels were upwards of sixty miles in length, and from six to seven miles of shafts had been sunk upon the lodes. This mine was remarkable for the very high temperature of its lower levels. The miners in some of the ends of the levels worked in temperatures varying from 110° F. to 115° F., the water rising in those levels being at the temperature of 120 F. This hot spring was remark

*Guide to Mineral Explorers in distinguishing Minerals, Ores, and Gems.' By Alexander M. Thomson, D.Sc. Sydney, 1869.

able for the great quantity of lithium which it held in solution. All the lower parts of the mine are now filled with water; a little tin is being obtained from the shallow levels; the machinery is being removed; and soon this scene of activity will become a silent ruin.

At Wheal Owles, in the mining district of St. Just, there have lately been discovered some valuable samples of the oxide of uranium, which have been sent into the market and realized high prices. The Gold-fields of Nova Scotia.-The declared returns of gold for the whole province to the end of the year 1869 are as follows:

The gross yield of gold in Nova Scotia during the past ten years has been 180,000 oz., representing, in round numbers, a value of 720,000l. sterling.

The produce of gold in Nova Scotia for the year ending 31st December, 1869, in all the gold-producing districts, is shown in the following Table: