CATALOGUE OF GEMS AXD PRECIOUS STONES. 



135 



LIST OF ROCKS FROM THE SOUTH AFRICAN DIAMOND MINES IN THE GARDNER F. 



WILLIAMS COLLECTION. 

 [From De Beers Consolidated Mines (Ltd.), Kimberley.] 



Below is given a complete list of the rocks from the various shafts 

 together with the depths below the surface at which they were found 

 to occur: 



DU-TOITS-rAN SHAFT. 



75897 

 75898 

 75899 

 75900 

 75901 

 75902 

 75903 

 75904 

 75905 

 75906 

 75907 

 75908 

 75909 

 75910 

 75911 

 75912 

 75913 

 75914 

 75915 

 75916 

 75917 

 75918 

 75919 



Decomposed basalt . 



Hard basalt. 



Coarse grained basalt. 



Fine grained basalt 125-132 



gfV^i ..." 132-161 



Black shale 161 _ 162 



Sandy shale lfi9 o fi4 



Black shale - 



Glacial conglomerate 



Glacial conglomerate at contact with quartzite 

 Glacial conglomerate with embedded boulder 



Quartzite - 



Diorite— (a) light color; (b) dark color 



Amygdaloid al diabase. Melaphyre (?) 



....do 



364-370 

 370 

 370 

 370-452 

 452-484 

 484-515 

 515-556 

 556-560 



4° ..'.'.'...... 560-750 



.do 

 .do 

 .do 

 .do 

 .do 



Dyke between hard rock and blue ground 

 Hard blue ground 



750-775 



750-775 



750-775 



750 



750 



750 



DE HEERS SHAFT. 



75920 

 75921 

 75922 

 75923 

 75924 

 75925 

 75926 

 75927 

 75928 

 75929 

 75930 

 75931 

 75932 

 75933 

 75934 

 75935 

 75936 

 75937 

 75938 



Quartzite 



....do 



Quartz porphyry 



Amygdaloid dyke (?) 



....do 



Quartz porphyry 



....do 



Dyke 



Dyke(?) -• 



Quartz porphyry 



Quartz porphyry dark 



Snake rock. Blue ground matrix 



Soft blue 



Hard blue 



do 



Biotite 



Concentrates 



800 

 1,200 

 1,400 

 1,440 

 1,480 

 1,520 

 1,560 

 1,600 

 1,640 

 1,680 

 1,720 



300 

 1,720 

 1,720 

 1.720 

 (') 



i From crater, about 1,400-foot level. 



