The way the geologist explained it to me, once brought up to the surface and the Lamproite goes through the winter exposed to freezing temperatures, weathering begins. I was told also, when the diamond mines were operating there, Lamproite diamond ore was put on piles, so it would weather away. The piles were stirred, you don't crush the ore. The ore becomes soft, the material is then run over a greased table for diamonds to stick, other stuff washes off. Weathered ore can be soft enough, you may crumble it with your fingers. Once weathered, it won't work as a specimen, about all it is good for is to crumble and fill up your gold pans. Here the black gold pans were only used to haul ore back to the car. All pieces got crumbled some to make sure they are weathered enough and not specimen grade. Also the broken up material takes up less space in the car.