The width of this reef varied from five feet to forty feet, and the average depth was about 200 feet. It was formed of a light olive-gray colored laminated shale, with a few rounded stones and angular pieces of basaltic rock, as well as occasional fragments of fine grained sandstone. These walls of shale were for the most part compact and unbroken, with a few straggling pieces of various sizes in the immediate vicinity. This rock was totally different from any forming the walls of the mine, and no similar shale has been recognized to my knowledge in any part of the country. At the southwest of the mine, in ground at that time belonging to Messrs. Lewis and Marks, there was a large floating reef composed of disintegrated igneous rock, resembling dolerite, which commenced near the main reef, and which jutted out to a distance of 120 feet in a northwesterly direction; this was a different rock from that forming the walls of the mine or any discoverable in the adjacent country. Veins or seams of crystallized carbonate of lime frequently run through the blue ground in all directions, in sheets more or less broad, and varying in thickness from a mere trace to two or three inches. The calcite is covered with a coating of a grayish white substance, very soapy to the touch, resembling steatite. Some of this lime contained cavities, having a fine deposit of iron pyrites which exhibited the most brilliant iridescence conceivable. One specimen which I saw was so beautiful that it was thought even worthy of presentation to royalty, and the owner gave it to Captain Harrell (formerly Cis-Molappo commissioner) for the purpose, but through some blundering or other it never reached its destination. Eventually, I believe, Captain Harrell, with the consent of the donor, caused it to be deposited in the South Kensington Museum. When Sir Henry Barkly was here in 1872 this was shown him, and he confessed it to be unique, in his opinion, and the prettiest specimen of the kind he had ever seen. When a wall or block of blue ground is dressed down and left standing with such a vein—or _greasy slip_, as it is termed—in it, it becomes highly dangerous, as all above the vein (at times an immense mass) is liable to come down without a moment’s warning.