Carbon leader in West Driefontein (shaft #5).
This is about 1 cm in width and very soft and greasy.
Photos from the Princeton Geomicrobiology Research Group's website--http://geo.princeton.edu/geomicrobio

Carbon leader at East Driefontein mine (shaft #5-level 48).
Thin carbon leader is primarily confined between conglomerate
foot wall and quartzite hanging wall. Bands of pyrite obvious in
conglomerate as are other layers of organic carbon.