Some losses are sustained in the death of cattle, which die with a disease called the mine sickness. Cows and horses, which are frequently seen licking around old furnaces, often die without any apparent cause. Cats and dogs are taken with violent fits, which never fail, in a short time, to terminate their lives. This is usually attributed, by the inhabitants, to the effects of sulphur, driven off from the ores in smelting. It is more probable that it arises from the sulphurous acid in its combination with barytes, which may operate as a poison to animals. The sickness is wholly confined to quadrupeds.[16]
The soil thrown out of the pits, at the abandoned mines, is found to produce some plants, and even trees, which are not peculiar to the surface. Such are the cotton-wood and the beech-grape, species which are usually confined to the arenaceous alluvions of valleys. And we think their growth here is not promoted by the mineral clay, which is manifestly of a fertilizing property, when cast on the surface; but to the disintegration of the sand-lime, producing a soil favorable to such productions. The sensitive brier, observed in the mine district, is evidently not of this class, as it is found remote from any mine excavations.
LOCAL POSITION OF THE SEVERAL MINES.
Since the first discovery of lead in this Territory, the number of mines has been much increased, and hardly a season passes without some new discovery. Every discovery of importance soon becomes the centre of mining attraction. As the ore is found in the diluvial soil, it is generally exhausted on reaching the solid rock; and after penetrating a considerable area of the surface with any, or but partial success, the locality is abandoned, and a new one sought. As the mines are worked without capital, and the ore is dispersed over a wide area, the number of localities is almost indefinite. Upwards of forty principal sub-districts are known, most of which are appropriately denominated diggings. The earliest discovery, at Mine à Burton, has been one of the most valuable, and still continues to afford the ore. Mine à La Motte has also proved an extensive deposit, and is still unexhausted. New Diggings, Shibboleth, and Richwoods, are among the discoveries of later date, which have yielded very large quantities of ore. But the mode of mining in the diluvial soil must exhaust it of its mineral contents, and direct miners, in after years, to the true position of the ore, in the calcareous rock. So long as the search continues in the soil, the business will partake of the uncertainty which now attends it, and which renders it rather an object of temporary enterprise, than a fixed employment.
In the search for ore in the soil, scarcely any uniform principles can be certainly relied on. Generally, rocky and barren localities are avoided, and large and deep beds of the red metalliferous clay sought for. The occurrence of crystallized quartz, or spars, on the surface, is regarded only as a general indication, but cannot be depended on to ensure local success. These masses are found to be distributed on and through the top soil, as other debris, being sometimes contiguous to, and sometimes remote from, ore. But they are never, so far as I have observed, found with the ore.
The method of searching for and raising the ore, is simple. Having fixed on a spot for digging, the operator measures off about eight feet square. A pick-axe and shovel are used for removing the earth. A practised hand will pitch the earth from a depth of eight or ten feet. A windlass and bucket are then placed over the pit, and the excavation thus continued. Small detached masses of ore, or spars, are often found in the soil, in approaching a larger body. The ore is the sulphuret, or galena. It has a broad, glittering grain, and is readily divisible into cubical fragments. It occurs in beds, or detached masses, which are deposited horizontally in the soil. They are often accompanied by the sulphate of barytes, or by calcareous spar; sometimes by blende, or iron pyrites. The ore is often connected with the barytic spar, indicating the latter to be a true matrix. The direction of these beds of ore appears to be irregular. Veins of ore are confined to the rock.
The variety of ore called gravel ore, differs from the preceding chiefly by its marks of attrition, and connection with diluvial pebble-stones. No spars have been noticed in these gravel-beds, although it is probable that a careful search might detect them.
The calcareous spar is most abundant in connection with rock diggings. It is translucent, or transparent, and often exhibits the property of double refraction. The miners, who employ their own conventional terms, call this substance glass tiff, to distinguish it from the sulphate of barytes, which is denominated tiff. Much of the radiated quartz of this district bears the marks of diluvial action. It is not uncommon to find masses of it, in which the angles of the crystals are quite defaced. Veins of ore in the rock correspond generally, in their course, I think, with the cardinal points, in the instances of their being pursued horizontally. But they dip at various angles with the plain, or sink perpendicularly into the rock.
The horizontal position of the ore-beds in the red clay soil, may be regarded as an evidence of its being a diluvial deposit.