Rouseite is an exceptionally rare lead-manganese selenite mineral typically found as delicate, pale yellow bladed crystals. It is primarily known from the Moctezuma mine in Mexico, where it forms in oxidized zones of selenium-rich deposits. Collectors usually seek it in micro-mount specimens due to the small size of the crystals.
Is this rouseite?
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 rouseite with a known reference. Rouseite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull, vitreous on cleavage surfaces.
- 4Match the color rangeCompare against the expected color range: yellow orange.
- 5Look at form & habitCrystal system: triclinic. Typical habit: microscopic crystals.
Often confused with
Rouseite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Rouseite leaves pale yellow, Mcalpineite leaves paler green; luster reads dull, vitreous on cleavage surfaces on Rouseite and adamantine on Mcalpineite.
How to tell apart: Denningite is the harder of the two (Mohs 4 vs. ~3); streak differs, so Rouseite leaves pale yellow, Denningite leaves white; luster reads dull, vitreous on cleavage surfaces on Rouseite and adamantine on Denningite.
Often found alongside rouseite
Minerals reported to co-occur with rouseite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂Mn(AsO₃)₂·2H₂O
- Mohs hardness
- ~3
- Density
- 5.73 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Dull, vitreous on cleavage surfaces
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Microscopic crystals
- Cleavage
- Perfect on {010} and {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare species found on a museum specimen, in a fracture cutting calcite-hausmannite ore, from a metamorphosed Fe–Mn orebody
Where rockhounds find rouseite
Classic worldwide localities
- Långban, Värmland, Sweden
Field-hunting tip
Where it forms: A very rare species found on a museum specimen, in a fracture cutting calcite-hausmannite ore, from a metamorphosed Fe–Mn orebody. If you start seeing trigonite, finnemanite, hausmannite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find rouseite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
