172 E. J. Dunn—The Transvaal GoMfields. 



consist principally of quartz. In the deeper workings white un- 

 altered siderite is found, with gold in it. There are very many 

 leaders at this locality ; at least thirty are already worked. They 

 run parallel, and range from one-eighth up to six inches in thick- 

 ness. Where they cut through certain beds of very fine, argillaceous, 

 dove-coloured shale, these leaders become extremely rich. The 

 veins generally contract at these intersections, and swell out above 

 and below. Often the width of the vein at such spots is not more 

 than one-eighth to one-fourth of an inch in thickness, and the whole 

 width is occupied by gold. Plates of solid gold, filling the veins 

 where so narrow, have been found, weighing from one to ten ounces 

 each. A few crystals of iron-pyrites (oxidized) occur in the quartz. 

 The " country " does not appear to have become mineralized back 

 from the veins. As at " Waterfall," the gold appears to have been 

 associated with the siderite, for which it had a greater affinity than 

 for the quartz, and seldom are the gold and quartz found intimately 

 blended. 



At "Ross Hill" iron-pyrites of large size — some crystals weighing 

 2 lbs. and more — and in groups of crystals weighing many pounds, 

 are abundant; the quartz of the veins is pitted with thin hollow 

 casts. All the pyrites are oxidized, and many of them show gold, 

 not only on the outside, but in the heart of the crystals. The 

 crystals are frequently modified dodecahedrons. 



At "Brom's Hill," "Ophir Hill," and the "Company's Eeef," 

 Grasskop, the quartz veins (generally " flat leaders ") are thickly 

 pitted with the cubic casts of pyrites ; and many of these veinstones 

 prove highly auriferous, the gold being impalpably fine (dust gold). 



At " King's Claim," Spitzkop, one of the richest spots yet found 

 on these Gold-fields, the gold occurs in a sort of soft breccia of 

 sandstone, shales, etc., interpenetrated by diorite in a soft state. It 

 is found in plate-like pieces, from a pennyweight up to two or three 

 pounds weight each. The gold is associated with a ferruginous 

 earth ; and quartz appears to be almost entirely absent, and is 

 certainly not the matrix in this instance. 



In " Mcintosh's Eeef," Swaziland, gold in small particles occurs, 

 associated with native bismuth, in the heart of the quartz, which is 

 somewhat greasy-looking, and occurs in a much older formation 

 (schist) than the veins previously mentioned. 



Crystals of gold occur at Woodward's leaders and at Silo and 

 Tait's Claims, Spitzkop. 



At "Frankfort" and " Hermansberg," on the Blyde Kiver, a 

 remarkable saccharoidal quartz is in parts richly auriferous ; oxidized 

 iron-pyrites and their hollow casts are numerous. The gold varies 

 from the size of a large pin's head to "flour gold." 



At " Pritchard's Keef," and " Rautenbach's Reef," near the 

 " Kantoor Diggings," a large area of diorite, in a decomposed state, 

 is penetrated in all directions with quartz-veins. Oxidized pyrites 

 are also present, and " flour gold " appears to be distributed through 

 the whole mass. 



As may be inferred, there are few localities where gold occurs 

 under such varying conditions as in the Transvaal Gold-fields. 



