ANCIENT SANDS 



103 



Fig. 28. Microphotograph of ancient pyrite— quartz sand, Witwaters- 

 rand, South Africa (x 45). White: grains of pyrite. Dark: grains of 

 quartz. At the top, lump of re-deposited older pyrite conglomerate. 

 Rounded borders of original pyrite grains within the older conglomerate 

 are still visible (from Ramdohr, 1958). 



