E. D. Clarke was the first mineralogist by whom crystallised graphite was observed and examined. As early as 1821, he described some graphite crystals from the mines at Borrowdale, in Cumberland. Clarke designated graphite by the name of " carburet of iron" or "plumbago," and stated its form to be that of an oblique four sided prism, the obtuse angle of which was found by measurement with the contact goniometer (" the common goniometer ") to be 118°.

The gradual decline in the production of copper from the mines of Cornwall and the consequent diminution of their number renders any discovery of a rare copper mineral an object of interest to all mineralogists.

Owing to the exhaustion of all the upper deposits, those products of decomposition—the beautiful arseniates and phosphates, &c. which adorn the cases of our national collection and those of private collections—are getting more and more scarce, and perhaps in the near future, so far as Cornwall is concerned, we shall have to rely for illustrations entirely on its past productions.

A specimen of crystallised quartz and albite has recently been acquired for the British Museum which has a few isolated crystals of this rare mineral dispersed upon it. Conclusive evidence that the specimen comes from Cornwall is supplied both by the appearance of the quartz and albite and by the presence of the clay-slate with which they are associated.

The mineral monazite or Turnerite has hitherto been discovered in few localities and never in the British Isles. Anatase, however, is mentioned in Greg and Lettsom (Manual of the Mineralogy of Great Britain and Ireland, p. 363) as occurring at Tintagel and near Liskeard in Cornwall ; and it is just possible that crystals of monazite may have been mistaken for anatase.

My attention was first directed to this rock by Mr. Cruickshank, clerk of works at Beaufort Castle, in July of last year, when, from the description he gave of it, I ventured to pronounce it barytes. Specimens were soon after this put into my hands by Mr. Cruickshank, when I found that my conjecture was a correct one. There was another mineral associated with the barytes, of which we will speak afterwards. The specimens received were so very fine, that I resolved to visit the locality to be able to describe its surroundings and procure specimens for myself. This I did in May last in company with two of my colleagues and Mr. John Ross, one of Lord Lovat's gamekeepers, and who I believe was the first to call attention to this new locality.

The crystals are of a similar length, though often considerably thicker than those described by Prof. Maskelyne (Phil. Mag. Jan. 1868), and his general description applies to those under consideration.

They are, however, ill-adapted for measurement, as single perfect crystals are rare. As a rule several crystals are longitudinally attached to one another, with slight radial divergence, in such a manner that it becomes difficult or impossible to discriminate between the reflections of their minute faces.

The proportion of actual carbon varies much in different samples. Some portions are stated to have analysed as high as 75 per cent., but, as will be noticed from the figures given below, the carbon may be much lower.

The samples to which this note refers were freshly cut from the quarries at Strontian. The mass differs much in quality, but is largely made up of the usual acicular groups. The colour of the mass as received varied, according to the composition, from a slight green shade where Strontianite predominated, to the more pure white of barium and calcium compounds.

The analyses were made from various portions, No. 1 being the selected Strontianite, No. 2 the more white portion of the mass.

In dana's System of Mineralogy, 5th Edition, 1883, page 747, the following description of this substance is given :—" Crystallisable in needles; butter-like in consistence; colour, white; melting point of impure native material, 47°, Brazier; but of material after solution in alcohol, 51°, Luck ; 52°-52°· Brazier ; easily soluble in alcohol or ether."

In the American Eagle Mine, Utah Territory, occur in intimate association with olivenite and other copper compounds, two copper minerals of an interesting and rare composition.

Covering the surface of often large pieces of more or less friable mixed arseniates, sometimes forming a complete green coating, are numbers of beautiful emerald-green globules. In consequence of the firm adherence of the base of the globules to the underlying gangue matter, it was difficult to obtain material pure enough for analysis, and therefore the results given below lay no claim to great accuracy.