Oxide of Titanium

Great Britain is richer in Minerals than might have been supposed; and I am happy to have it in my power to add still another lo the catalogue, by favour of my friend W. Lowry, Esq., whose kindness I have mentioned before. This gentleman brought it from near Snowdon last summer. When I figured the Menachanite, tab. 277, however confident I might be that many Minerals, as yet only discovered as foreign productions, might be added to the British list, I must own I did not expect to find Titanium, except in the Menachanite, where it is known, by the aid of chemistry, to exist in the form of an Oxide combined with Iron, The satisfaction of seeing it in a regular formation, distinctly identified and crystallized, is very grateful. It is most usually found in Hungary; but the present specimen more nearly resembles the specimens from St. Gothard, being on a gangue of Quartz and Adularta, I do not know of any other having been found in Great Britain. It is of an intense semi transparent red, showing occasionally a brilliant reflection. The crystal is represented distinctly, and rather large, at the bottom of the plate, showing the principal faces deeply striated, with the bevellings, truncations, &c. The Quartz upon which it is found is rather elegantly crystallized and grouped; but could not be drawn with every advantage to show both subjects, and the white Adularia, which is in small crystals, somewhat like those in tabs. 211 and 212 in form, much resembling that found abroad, being nearly as transparent as the Quartz, which adds much to its rarity as being British.

Oxide of Titanium when crystallized is said to contain little or no Silex. Its specific gravity is from 4.1025 to 4.246. It is soft, hut not easily scratched with a knife. The fracture in the present specimen is vitreous, nor could we discover any other, though Haüy says its primitive form is an upright prism with square bases. The most conspicuous faces of the largest flat crystal on the specimen are shown in the lower figure, the three angles of incidence that could be measured were ab, bc, cd; the first measuring 142°, the second 130°, and the third 147°.

There are many minute irregular fragments about the gangue, and two crystals remarkable for being flattish in the pyramidal end of the large Quartz crystal, one of which is reflected three times, or seen at the same time in three of the faces, which serves as an example of the multiplying quality of faceted subjects, very convenient in this where the substance is scarce. It is infusible by the blowpipe, but becomes blackish and opaque.

Since writing the above, I have been presented with a superb specimen of Quartz, on which are two or three crystals of this Oxide of Titanium, by my kind patron the Right Hon. the Earl of Dartmouth, from the same place. This specimen also has some Adularia about it.