Amethyst Silicon Azurite Bismuth samples from Peter's collection

Amethyst, native Silicon, Azurite and native Bismuth samples from a friend's collection, clockwise from top left. All of these are naturally-occurring minerals that you can pick up from the surface, if you're looking in the right place. Amethyst and Azurite are used as gem stones; Silicon and and Bismuth are two of the few elements which can be found in pure solid form in the ground. Crystalline Bismuth is unusually dense so the sample feels "heavy" compared to expectation. Thanks Peter.