Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/131

From Wikisource
Jump to navigation Jump to search
This page has been validated.
121
Mr. William Phillips on the Veins of Cornwall.

The early discovery of iron pyrites and portions of yellow copper ore mingled with a large quantity of blende is considered a favorable omen for copper. Blende, as has already been noted, is by the miner called Black Jack; and ‘Black Jack,’ he says, ‘rides a proud horse,’ a phrase become proverbial, from blende being often found to lie above, in a vein rich in copper beneath. Vast quantities of it were found above the ore in the productive copper mine Huel Towan, as well as in that called North Bennar. The early discovery of lead is also considered a good symptom; very many tons of it were sold from Huel Alfred in the states of sulphuret and carbonate. Iron pyrites at a small depth is, also considered a favorable symptom for copper in depth, as was proved among many others in the rich mines of Crenver and Huel Virgin; but when it proves solid, it has often discouraged the miner and induced him to abandon the vein. The cutting of a ‘good course of water’ is esteemed no unfavorable circumstance, especially if it be warm, and it is not uncommon to find water issuing from one part of a vein of a temperature sensibly higher than that in other parts of it. So greatly indeed does water abound in rich veins, that on extensive and deep mines are mostly seen two, three, and even four steam engines, for the purpose of drawing it, the cylinders of which are from 30 to 66 inches in diameter. If a vein be particularly rich, it is considered to omen well for the parts of other veins immediately north and south of its riches; to express which the phrase of “ore against ore” has been adopted.

It would scarcely be correct to say that the early discovery of tin in a vein is a good promise for copper in depth, but it is certainly true that tin is frequently, if not mostly, found at a small depth in veins, afterwards proving rich in copper. Among many other instances of this that might be quoted, are the two deep and

Vol. II.Q