Desautelsite is a rare magnesium-manganese carbonate member of the hydrotalcite group. It is typically found as small, orange, platy crystals or as crusts forming in association with serpentinized carbonate rocks.
Is this desautelsite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch desautelsite with a known reference. Desautelsite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale orange.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: bright orange.
- 5Look at form & habitCrystal system: trigonal. Typical habit: euhedral crystals, pseudo hexagonal.
Often confused with
Desautelsite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Desautelsite leaves pale orange, Pyroaurite leaves white; luster reads pearly on Desautelsite and waxy to vitreous, may be pearly on Pyroaurite.
How to tell apart: Streak differs, so Desautelsite leaves pale orange, Stichtite leaves very pale lilac to white; luster reads pearly on Desautelsite and waxy to resinous, somewhat pearly on Stichtite.
Often found alongside desautelsite
Minerals reported to co-occur with desautelsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₆Mn₂(OH)₁₆(CO₃)·4H₂O
- Mohs hardness
- ~2
- Density
- 2.13 g/cm³
- Colors
- Streak
- Pale orange
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Trigonal
- Crystal habit
- Euhedral crystals, pseudo hexagonal
- Cleavage
- Perfect on {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- 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)
Where rockhounds find desautelsite
Classic worldwide localities
- Cedar Hill quarry, Lancaster Co., Pennsylvania, and at the Coalinga asbestos mine and the Herman Akers prospect, New Idria district, San Benito Co., California, USA
- Shiraki, Mie Prefecture, and Konomori, Kochi Prefecture, Japan
Field-hunting tip
Where it forms: 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). If you start seeing brucite, artinite, aragonite in float, you are in the right ground. Typical habit: euhedral crystals, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify desautelsite?+
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What rocks look like desautelsite?+
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Find desautelsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
