The green grains are olivine, the black are basalt, and the white are possibly bits of shell. Green sand is reasonably rare; the southern tip of the big island of Hawai’i is the most common place to get it.
If you want to add to Mouser’s collection, you can send him a small sand sample (about the size of a film canister) here:
128 Rover Blvd.
Los Alamos, NM 87544