This chalky stone gets its name from the environment in which it forms—the desert—and from its distinctive shape, which closely resembles the petals of a rose; it truly looks like a flower born in the sand. Specifically, however, it is a sedimentary formation that forms naturally under the environmental and climatic conditions typical of desert regions.

When, beneath the layer of sand—at a depth ranging from a few tens of centimeters to just over a meter— there is a small amount of moist gypsum, the sandy surface may be heated by the scorching sun, whose heat penetrates until it comes into contact with the moist gypsum, causing it to evaporate. It is during this process that the phenomenon of crystallization can begin as the gypsum rises to the surface. This is how desert roses form beneath the sand; in some cases, they may be carried to the surface by the wind, and if not collected, they will dissolve when exposed to rain.

source: www.rudolfsteiner.it