g_axelsson said:Hard to say what it is, but it doesn't look like kimberlite to me. More like a mica schist.
But then I have no experience with rocks from South Africa. You should try to find a local mineralogical society or rock club, they could probably help you with identifying the rock. It is so much easier to do it if you can hold the rock in your hands and do all kinds of testing.
Göran
Enter your email address to join: