Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/149

From Wikisource
Jump to navigation Jump to search
This page has been validated.
Mr. William Phillips on the Veins of Cornwall.

branches or strings are occasionally observed to strike into the vein from the north or south, which, it seems probable, have before diverged from the same, or some neighbouring vein, (Pl. 6. fig. 5.) It is not certain that copper veins are equally subject to this circumstance as are those of tin. In Polgooth and Carnmeal tin mines, their effect was the sudden enlargement of the load to what is termed a floor of tin, twelve feet or more in breadth, but without the determinate walls usually observable in regular veins. A floor of tin rarely continues for any considerable length or depth, and the load is generally soon found to resume its usual size and appearance. From the common effect of this kind of branch or string, it is generally known by the term leader.

The Contre.

There occurs still another species of vein, of which the course or direction is generally about north-east and south-west, and which therefore is oblique in respect to all other veins; from this circumstance I presume it to have obtained the name of Contre or Counter. They are mostly, if not always, metalliferous; several instances have occurred of their being remarkably rich. Two instances will be noticed in the annexed descriptions of Huel Alfred and Herland mines, in both of which they were very productive of copper ore.

It may here be noticed, that in the former of those mines, the regular or east and west vein was disturbed by the contre, and for some distance totally disappeared on the west. In the latter, both the load of the regular vein and that of the contre were enlarged, and became more productive by uniting.