sulfates
Desert rose
Ca(SO4)·2H2O
- Also known as
- sand rosegypsum rosebaryte rose
- Crystal system
- monoclinic
- Hardness
- 2 on the Mohs scale
- Lustre
- dull
- Colour
- Sandy brown to buff
- Where it forms
- In arid basins where gypsum crystallises from evaporating groundwater within sandy sediment, producing intergrown bladed crystals in a rosette.
- Chiefly from
- TunisiaMoroccoMexicoOklahoma, United States
Why it is that colour
The colour is sand. Desert rose crystals grow around and incorporate the grains they form in, so a rosette is roughly half sand by volume.
Safety
Safe to handle. Extremely fragile, soft, and water-soluble — a desert rose left in water will fall apart.
Where it comes from
Tunisian and Moroccan material dominates and is very cheap. Some rosettes are baryte rather than gypsum, and the two are sold interchangeably despite being different minerals.
Historical use
None of significance.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
No traditional attribution. It is a modern collector and tourist item, sold in quantity across North Africa since the twentieth century.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
A desert rose is a good demonstration that crystal habit — the shape a mineral grows in — is a product of circumstance rather than an intrinsic property. Gypsum growing in open water makes clear blocky crystals. The same gypsum growing inside damp sand makes flat blades that push the grains aside and trap them, and the blades intergrow into a rosette.
Same mineral, same formula, three entries in this collection, three completely different-looking objects. What varies is not the substance but the room it had.
Identity checked against IMA-CNMNC master list, June 2025.