Desert rose is a type of sedimentary rock in which sand particles are connected to each other by gypsum mineral. Gypsum or calcium sulfate is a common evaporative mineral with the chemical formula CaSO2. 2H2O is formed in dry sandy conditions such as evaporation of a shallow saline basin. This mineral is a common mineral in desert areas and only crystallizes in the form of rose in some desert areas.

 

Formation of derest rose:

Sea water is a solution rich in all kinds of salts; 80% of its solutes are sodium chloride and 4% are calcium sulfate. When water evaporates due to sunlight, dissolved salts are deposited in the water. Sulphate and calcium-rich waters can enter porous coastal sand sediments from the sea due to capillarity. By evaporation of water, gypsum mineral is formed and it connects the sand particles together in the form of a cement and forms desert rose. At first, desert rose is formed at the level of underground water at a depth of one meter from the surface of the earth. As a result of erosion, desert roses appear on the surface of the earth after some time. These processes last for tens or hundreds of years.

 

 Desert rose is found in some countries such as Saudi Arabia, Tunisia, Algeria, Egypt, Libya, Morocco, Jordan, Qatar, Mexico and also South Africa.

 

In the geology department of the Natural History Museum, you can see different types of gypsum minerals collected from different regions of Iran.