Mineralpedia Details for Desautelsite

Paul Ernest Desautels is the namesake of this mineral as the former Curator of Mineralogy at the National Museum of Natural History in the Smithsonian Institution in Washington D.C., USA. Desautelsite is a rare mineral that occurs only in the United States in localities in California, Maryland, and Pennsylvania, and in Japan at Kohnomori in Kochi City on Shikoku Island. It occurs as an abundant mineral in fractures in serpentinite breccias with other secondary magnesium minerals in its California localities, and in ultramafic rocks in faults through sediments in Japan.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/desautelsite.pdf

Formula

Mg₆Mn³⁺₂CO₃(OH)₁₆·4H₂O 

Crystal System

Trigonal 

Crystal Habit

Euhedral Crystals, Pseudo Hexagonal 

Cleavage

Perfect, None, None 

Luster

Pearly 

Color

bright orange 

Streak

light orange 

Class

Trigonal 

Hardness

2 

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Mindat

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Fine bright orange crust of Desautelsite composed of thin platy crystals to less than 0.2mm. Desautelsite is the trivalent Manganese analogue of more common Pyroaurite. It is a hydrotalcite and a carbonate with thin, microscopic platy crystals