Hanksite is a rare anhydrous chloro-carbonate of potassium and sodium first described in 1885. It is very unusual in that it consists of both sulfate and carbonate ion groups, which has led to some confusion about which group to place it in. At any rate, it forms nice crystals in evaporite deposits. This one is from the type locality at Searles Lake, and it is just superb in every way: doubly-terminated, with two fine, flat terminations; perfect hexagonal form; nice translucency; and, really impressive size. If you don't have one, here's a really fine one! 8.5 x 5.5 x 5 cm