I’ve been out in the field for the past couple of days (the South African weather having picked up just in time to completely fry me), and my travels have yielded me a deskcrop that I’m very proud of:
What do you think it is? Just to show that I’m not completely heartless, here’s a picture of the outcrop from which it was obtained:
This is potentially pretty difficult, so I may post another clue over the weekend. Go to it in the comments.