Mallardite is a rare manganese sulfate mineral that typically forms as delicate, fibrous efflorescences or crusts in mine workings. Because it is highly soluble in water and prone to dehydration, it is difficult to preserve and requires storage in a controlled, dry environment.
Is this mallardite?
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 mallardite with a known reference. Mallardite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless, white, light pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Mallardite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mallardite
Minerals reported to co-occur with mallardite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnSO₄·7H₂O
- Mohs hardness
- ~2
- Density
- 1.846 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- On {001}, good; on {110}, probable
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral formed by oxidation of Fe–Mn sulfides and carbonates under conditions of saturated relative humidity; typically post-mine, when it may be seasonal
Where rockhounds find mallardite
Classic worldwide localities
- Lucky Boy mine, Butterfield Canyon, Bingham district, Salt Lake Co., Utah, USA
- Bayard area, Central (Bayard) district, Grant Co., and in the Lake Valley district, Sierra Co., New Mexico, USA
- Moon Anchor mine, Cripple Creek district, Teller Co., Colorado, USA
- Jokoku mine, about 60 km southwest of Hakodate, Hokkaido, Japan
- Broken Hill, New South Wales, Australia
- Chvaletice, Czech Republic
Field-hunting tip
Where it forms: A rare mineral formed by oxidation of Fe–Mn sulfides and carbonates under conditions of saturated relative humidity; typically post-mine, when it may be seasonal. If you start seeing manganoan melanterite, jokokuite, ilesite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mallardite?+
Where is mallardite found?+
What rocks look like mallardite?+
What minerals are found with mallardite?+
What kind of rock does mallardite form in?+
What is mallardite used for?+
Find mallardite on the map
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