Phosphate of Iron

Although I have figured a crystallized Phosphate of Iron in tab. 3 of Exotic Mineralogy, I am pleased, before I finish British Mineralogy, to find it produced in our island, and notice it accordingly. Foreseing such occurrences, I did not proceed with Exotic Mineralogy, but determined to finish British Mineralogy first, that it might include all the species possible.

The crystals are very much elongated laminæ grouped into prisms in varied angles, the ends of the laminæ terminating them somewhat obliquely, but not regular enough for determination; they separate easily into very thin plates that allow of folding, transversely resembling some of the finest Gypsum, but more pliable; it is tender like it, and easily scratched by the nail; the thin plates, separate, have a lightish blue cast in the thinner parts, and darker when viewed through the thicker edges: the mass appears of a bottle or dark green colour when viewed through the sides, but if viewed endwise or lengthwise, mostly blue: lustre glassy and very great: there is often sufficient space for refracting colours betwixt the laminæ.

The Phosphate of Iron in this specimen is accompanied by Carbonate of Iron in small crystals on Schist with Quartz, Chlorite, &c. Tts external resemblance to Talc was such as to have met with a general consent to its being so; but Dr. Wollaston has proved it to be Phosphate of Iron, and it is truly interesting to see it so accompanied by the Carbonate, Now do we see that Chemistry aids description; and though a substance may be identified without it, yet some of its help is absolutely necessary to warrant conclusions. These specimens are in the possession of my kind friend Mr. Heuland, whom I rejoice to find pleased to lend his most valuable specimens for the benefit of science: they were found about 55 fathoms from the surface in driving an end from north to south in Huel Kine in Cornwall.