Pros: What is a kimberlite dyke? 

IS: Dykes are where the kimberlite never reached the surface.  Kimberlite dykes are in Tongo Field, near Kenema.  Kimberlite fissures are similar.  Kimberlite pipes in Sierra Leone are concentrated around Kono.

Pros: Tell us about mining in Sierra Leone.

IS: Beginning in 1950s, SL government allowed licensing of artisanal diamond mining – small mining by hand using only a shovel and sieve.  Beyond licensed mining, there was a lot of illicit mining using these techniques.  Industrial mining digs down into the kimberlite pipes, which requires major capital investment.  Semi-industrial mining means that diamonds are below the surface, requiring modest investment in equipment such as bulldozers. 

Pros: What are tailings?

IS: Remains of mines. The Sierra Leone Selection Trust equipment only picked out diamonds larger than a particular size.  The tailings from that mining can be re-mined for the smaller diamonds.