185/.] RUBIDGE NAMAQUALAND. 235 



Rock-structure of the district. — In this part of the country the 

 rocks are chiefly gneiss, with here and there small patches of mica- 

 schist. Some granite occurs ; but not, as far as I am able to judge, 

 in the form of dykes ; indeed its relation to the gneiss is obscure. 

 Hornblende and actinolite in many varieties occur about the mines, 

 and steatite abounds in some parts. The hypogene rocks are over- 

 laid by clays, shales, and a mass of sandstone, which appears to be 

 continuous with that which caps Table Mountain. 



The granite and gneiss. — I cannot perceive that the gneiss under- 

 goes any change in the vicinity of the mines. Specimens 92 and 93 

 of the collection * sent to illustrate these observations will, I believe, 

 be found to differ from 95 only in having undergone decomposi- 

 tion, which latter is a fair sample of the rock of the country ; and 

 these two were taken from within a few yards of each other on 

 either side of the axis of Concordia Mine (Hesther Maria). The 

 centres of the axes are very frequently composed of granite, but 

 this is not always the case ; and I do not know that I have seen 

 any mine where granite is not to be found in the works, though 

 the gneiss may meet in well-defined character and with opposite 

 dip over it. In this country I have stood on granite, vrith gneiss 

 forming the sides of a ravine on either hand, with continuous dip. 

 I have also seen hornblende-schist (felspar and hornblende) passing 

 insensibly, as it were, into syenite and greenstone of perfectly well- 

 marked characters, near Pella. The ravine just noticed is between 

 Pella Missionary Station and a detached station called Klein Pella. 



Metalliferous '' runs" and axes. — The surface of the metalliferous 

 *' runs," whether formed in the centre of granite or not, is much 

 fissured in the direction of the magnetic meridian — nearly, as well as 

 in others ; and these fissures, together with the lamination-planes of 

 the gneiss (indicating dip and strike), give the only appearance of 

 regularity to the deposits of ore which they present. The surface, 

 thus cross-fissured, is softened to a considerable degree, and generally 

 presents a dark-brown, iron-stained aspect, which is often visible at 

 a distance of a mile or two. The rocks, in fact, over these axes have 

 undergone great decomposition, and some of their surfaces often 

 present a bright-green stain of sihcate of copper. Lumps of oxide, 

 of a rounded form, are often found on the surface ; probably half a 

 ton has been picked up on the hill on the declivity of which the 

 works of this mine (Springbok) are carried on. Some fine specimens 

 of the same ore, of a still more compact nature, and containing as 

 much as 60 per cent, of copper, are found in the fissures or on the 

 surface. When these are followed downwards, they often widen at 

 first into good-sized veins, which give promise of a rich return of 

 ore; but when a depth varying from 4 or 5 to 25 feet is reached, 

 they are generally found to contract, and sometimes they terminate 

 abruptly. In either case, they are rarely traced beyond that depth, 

 though occasionally the dip of the rock carries them somewhat 

 further. At a greater depth, purple sulphurets are found ; and these 



* In the Society's Museum. — Edit. 



