Pirssonite crystal, a rare, sharp, buoyant sodium calcium carbonate. As usually happens, it presents whitish efflorescences on the surface. A very unusual carbonate from the type locality at Searles Lake, a large, nearly 20 km dry lake in the Mojave Desert. On its western coast is the mining community of Trona. Borax has been mined since 1873. Today sodium sulfate, sodium carbonate and sodium chloride (halite) are also produced.