396 zrxc .\xn li^ad okposits of i'.rokkiV htll. 



mine and in ferruginized Plimestones of Kopje No. 2 small 

 groups and isolated crystals of descloizite were found to be 

 rather common. 



Vanadinitc forms coraloidal growths and encrustations on 

 the surfaces of the bone-breccia of the cave in Kopje No. i. It 

 is intimately associated with hopeite. and is generally overgrown 

 by that mineral. 



Limonite is exceedingly common in Kopje No. 2, being the 

 substance of the cavities in which the beautiful pyromorphite and 

 tarbuttitc occur. It is very cavernous and pseudostalactitic. 

 The mineral as yellow ochre is also common intermixed with 

 hemimorphite, cerussite, etc., in the gossan of Kopjes i and 3. 

 Massive limonite was noted in some of the drives of No. 2 Kopje. 

 A little Gothite is also present. 



Quartz, as implanted crystals lining small cavities in the 

 gossan of Kopjes 3 and .\, occurs abundantly. To a lesser extent 

 it is similarly present in Kopje No. i. 



Chalcedony is less common than c|uartz, but large masses are 

 present in Kopjes 3 and 4. 



Psilouielane, in the form of wad, is present in Kopje No. 2 

 in small amount. 



Malachite was found in very small amount in Kopjes i and 2 



/Acui'lte also was found, in very small amount, partly 

 coating galena altering to cerussite. 



Chrysocolla also was noted in Kopje No. i, together with a 

 little f Dioptase, which may, however, have been confused by 

 the writer with f Copper phosphate, the pale-green mineral noted 

 by ]\Ir. Spencer as occurring in small bright-green ( monoclinic?) 

 crystals, and suggested by that author to be a copper phosphate. 

 This mineral was noted in very small quantity in cavities in the 

 surface ore of Kopje No. i. 



Dolomite is believed to be present in coarse aggregates in 

 Kopjes Nos. T and 2. but it was not found /// situ by the writer. 



A white, pearly-lustred mineral in minute squat crystals 

 present in Kopje No. 2 is believed to be a phosphate of zinc, but 

 it is not yet identified. The form of the crystals does not seem 

 to conform with any 'of those of previously described zinc 

 phosphates. 



No silicates of lead were detected, neither was greenockite 

 found. These minerals were carefully searched for. Willemite 

 is suspected, but could not be found by the author. Alelaconite 

 is suspected to be present in small quantity. 



It is stated that traces of gold and silver have been detected 

 by assay of material from Kopje No. t. 



V. Origin of the Pho.sphates and Vanadates. 



By plotting out the results of the survey of certain of the 

 minerals, important considerations concerning the relationship 

 and origin of the beautiful phosphates and the vanadates are 

 suggested (see Figs. 3 and 4). Firstly, the phosphate minerals 

 of Kopje No. 1 are clearly restricted to the immediate 



