Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/191

 Rh of very recent formation. This fact, which Dr. Kidd conceives to be unique in its kind, appears less extraordinary, since the discovery by Morichini of fluate of lime in the enamel of some fossil elephants' teeth, where it was mixed with phosphate of lime and gelatine.

In the mine called Stony Gwynn, in the parish of St. Stephens, violet fluor is found combined with vitreous quartz, phosphate of lime, and yellowish foliated talc, forming a very hard and compact rock, which constitutes the saalbande. This rock is certainly not the same with that forming the mass of the mountain, although it resembles it, thus demonstrating its antiquity. The middle parts of the vein, in the same mine, although more recent, are however, in my opinion, of much earlier formation than the greater number of the other mines in Cornwall. It is a rock which has some resemblance to the topaz-rock of Werner; and is composed of a fine quartz, more or less granular, with yellowish or white foliated talc. In the middle part of the vein, there are frequent cavities, lined with rock crystal, and crystallized apatite. This assigns a pretty remote age to the last-mentioned substance as well as to the talc, which is conformable with the ideas of Werner. The schorl rock may perhaps be considered as a vein-stone, or rather as forming a saalbande.

Carbonate of lime is of very rare occurrence it Cornwall; I saws very fine specimen of schiefer-sparth, (slate-spar, or chaux carbonatée nacrée of Haüy) in the collection of M. John Williams, which had been found, I believe, in the tin mine of Polgooth.

Such are the few observations I had to make on the ores and