The first grid is a word search for rock or mineral names—the flavortext referring to original composition and the title can be parsed as Beryllium Mine.

Each rock or mineral name is an IMA-approved name ending in –lite or –nite and also containing at least one rebus. Each nite or lite is used in exactly one rock or mineral name.

The unused letters read THESE UNUSED LETTERS WONT HELP YOU HAVE FOUND ALL WORDS TRY SOMETHING NEW

The second grid is comprised of images of elements from the photographic periodic table at http://periodictable.com/.

After overlaying the rebus grid on the elements grid and shading only the elements that appear in a given mineral’s composition, the grid reveals the answer PLYMOUTH ROCK