Page:A sketch of the physical structure of Australia.djvu/59

47 arenaceous claystone. The galleries of the mines are dug with pickaxe and spade, and the rock can be easily cut in all directions with the knife. Some of it hardens rapidly when exposed to the air, so that when dug out and cut into shape it forms in a few days a very good building stone. In the galleries of the mines, the rock, which could only be called an argillaceous sandstone, had a "stripe," or appearance of bedding similar to that so often seen in clay slate. The general dip was W. 10&deg;, S. at about 15&deg;; but the rocks were said to have a quaquaversal dip of about that amount in this locality. There were eight lodes of copper ore, running parallel to each other, in the direction of N. by E. and S. by W., seven of them nearly perpendicular, but one in the plane of the bedding. The ore consisted of blue and green carbonates, and black oxide, the latter most abundant in the deeper parts of the mine. The rock is said to get harder as they descend. The greatest depth they had attained in 1845 was 16 fathoms, or 96 feet, at which depth they got some water, very clear, but very salt, and aluminous to the taste.

About forty miles north of Kapunda is the celebrated Burra Burra mine, which I had not time to visit; but which was described to me by Mr. Kingston, of Adelaide, who was concerned in its management. He said the general rock of the country was clay slate there also, but the copper ore, instead of a regular system of lodes, was found in one large mass, occupying the surface of the ground for many hundred square yards. Holes had been sunk into it, and in one place, at the depth of 26 feet, they had pierced through the ore into a similar soft rock to that which forms the "country" (as miners term it) at Kapunda. Other openings had been blasted and quarried to a greater depth in the copper ore without reaching its boundary, nor were its limits at the surface exactly known at that time. Some distance from the working, a stout quartz vein, running about N.N.E.