This is one of the "treasures" in my treasure tray.
Desert rose is the colloquial name given to rose-like formations of crystal clusters of gypsum or baryte which include abundant sand grains. The 'petals' are crystals flattened on the c crystallographic axis, fanning open in radiating flattened crystal clusters. (thanks Wikipaedia). This one was picked up in the Kalahari in South Africa.
Fascinating bit of information to accompany this fabulous photo. All the textures of the crystals make it a great subject for black and white photography.