Desautelsite Locality: Artinite pit, Clear Creek area, New Idria District, Diablo Range , San Benito County , California , USA ( Locality at mindat.org ) Size: 3.6 x 3.4 x 2.6 cm. A reference specimen with massive desautelsite in matrix. Ex. Martin Zinn Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Desautelsite
Desautelsite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Mg₆Mn³⁺₂(CO₃)(OH)₁₆·4H₂O.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Hydrotalcite structural group.
Key properties: Mohs hardness 2; specific gravity 2.13; Pale orange streak; optically uniaxial.
IMA symbol Des, IMA status: approved, named in 1978.
Abundantly, in fractures in serpentinite breccia, with other secondary magnesium minerals, the last mineral to form (California, USA); in ultramafics in faults in sediments (Shiraki, Japan).
It is found associated with Brucite, artinite (California, USA); aragonite, hydrotalcite, rhodochrosite, manganese oxides (Shiraki, Japan).
The mineral was named to honor Paul Ernest Desautels (1920–1991), Curator of Mineralogy, National Museum of Natural History (Smithsonian Institution), Washington, D.C., USA.