The Great Salt Lake has gypsum crystals that have been nicknamed “dirty diamonds” made of hydrous calcium sulfate. Such crystals are found as floater crystals in clay beds, where they fully form without being attached to matrix. The dirty diamonds are lenticular (lens-shaped) crystals in the monoclinic system, with a shape that resembles a diamond.

The crystals may trap clay inside when forming, coloring a specimen brown or gray, or making it opaque. These clay inclusions sometimes form hourglass formations inside a crystal. These inclusions are what give the crystals their nickname, dirty diamonds.

These were dug near the spiral jetty on the north side of the lake.