Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/158

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3. In those places which have been thought to prove that granite veins were formed in the same way as metallic veins, they have always been at a considerable depth, such at least, as might reasonably induce us to suppose, that they were very near the main body of the granite.

4. These granite veins, whether they are found at the surface or at a greater or less depth, are in Devonshire and Cornwall, invariably directed from north to south, which is a direction opposite to that of the metallic veins, but quite conformable with the mode of deposition of the grauwacke on the mass of granite which forms the low mountain chain of Cornwall.

5. These subterraneous granite veins are rarely metalliferous, but when they do contain a metal, it is always tin, which is known to belong to the oldest formation, and which sometimes forms one of the component parts of the granite.