Desert rose (crystal)

A desert rose is an intricate rose-like formation of crystal clusters of gypsum or baryte, which include abundant sand grains.

The crystals form a circular array of flat plates, giving the rock a shape similar to a rose blossom.

Sand roses are found in large numbers in surroundings of the salt lake of Chott el Djerid in South-West Tunisia, as well as the neighboring regions in Algeria and Ghadames, Libya.

As the sea retreated, baryte precipitated out of the water and crystallized around grains of quartz sand.

The largest recorded by the Oklahoma Geological Survey was 43 centimetres (17 in) across and 25 cm (10 in) high, weighing 57 kg (125 lb).