Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/145

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135
Mr. William Phillips on the Veins of Cornwall.

that it is as it were broken into small strings or branches. By a careful examination of the nature and direction of these, the miner is indeed sometimes enabled to find pretty readily that part of the load which is on the other side of the cross vein, but he is often baffled. Instances have occurred in which the load has, as it were, been turned. by the cross vein, so as to form what the miners term an elbow.

Not only does the substance, whatever it may be, of the cross vein, almost uniformly pass through that of the metalliferous vein, but it is often found so to interrupt its course, as, in the phrase of the miner, to heave that part of the vein, east or west of it, a few inches, or even many fathoms north or south: and as the metalliferous vein is frequently found to be poor on one side of the cross vein, though rich on the other, its occurrence sometimes not only baffles the skill of the most experienced miners, but also causes much loss and vexation, as the annexed account of some peculiarities in the veins of Tol Carn, Huel Jewel, and Huel Damsel mines, will shew.

Though the cross courses, or north and south veins, are rarely found to be metalliferous, or even to yield any of the ore of the east and west veins through which they pass, a general exception was found to exist in those of the great tin mine near St. Austle, called Polgooth, in which, I believe, they universally produced tin. Two of the cross veins in Herland and Drannack mines yielded silver—one of them very sparingly, in the other it was accompanied by other metallic substances: the quantity of silver amounted in value to 8 or £9000. Pryce says[1] that cobalt has been found in veins of this description, that others have been worked for lead, and [2] that the direction of antimonial veins is

  1. Min. Cornub. p. 50.
  2. Ibid. p. 50.