Trouble with Amethyst

While trying to complete the GEODIG while collecting in London, up on the rocks on the left of the screen, using a pick, with my avatar shouting I found something, a piece of amethyst appears on the screen, but it never makes it into my rock collection. What am I doing wrong here? I have ask a helper and the helper suggested that I contact Whyville. I do not readily see a way to make that contact.