Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/185

 Rh mentioned, I cannot say. Manganese as well as antimony occurs in primitive and in secondary mountains, and the different formations of it appear to belong to a middle age.

The lead formation is of very small extent in Cornwall, it is confined to the low parts of the county. This metal is known to occur particularly in calcareous countries, rarely in primitive rocks; it is one of those metals most universally spread over the surface of the globe, especially in the state of galena. Werner conceives that the munerous formations of this metal are of very different ages.

The ferriferous oxide of titanium belongs almost exclusively to primitive countries. The locality of the menachanite proves nevertheless, that it may also be met with in secondary countries. The naturalist, to whose accurate researches we are indebted for the discovery of the menachanite, has also observed it in a kind of sonorous petrosilex, which I consider as the clinkstone of Werner, and which had been picked up in the neighbourhood of south Brentor in Devonshire, where it is found in blocks on the surface of the fields. We know in fact, that the oxide of titanium exists in a great number of rocks, even in granite.

With the exception of platina, mercury, molybdena, tellurium, tantalum, columbium and cerium, Cornwall affords indications of all the other known metals, in one shape or other, in mass, forming deposits, or as adventitious substances in the veins.