Redingtonite is a rare hydrated sulfate mineral typically found as delicate, fibrous efflorescences in mine workings. Because it is highly soluble in water, it must be stored in a dry, sealed environment to prevent dehydration and crumbling. It is primarily sought by advanced mineral collectors specializing in secondary sulfate species.
Is this redingtonite?
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 redingtonite with a known reference. Redingtonite 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: silky.
- 4Match the color rangeCompare against the expected color range: white, light violet, light purple.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous.
Often confused with
Redingtonite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside redingtonite
Minerals reported to co-occur with redingtonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeCr₂(SO₄)₄·22H₂O
- Mohs hardness
- 2
- Density
- 1.761 g/cm³
- Colors
- Streak
- White
- Luster
- Silky
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of pyrite
Where rockhounds find redingtonite
Classic worldwide localities
- Redington mercury mine, Knoxville, Napa Co., California, USA
Field-hunting tip
Where it forms: An oxidation product of pyrite. If you start seeing magnesiocopiapite, pyrite in float, you are in the right ground. Typical habit: fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify redingtonite?+
Where is redingtonite found?+
What rocks look like redingtonite?+
What minerals are found with redingtonite?+
What kind of rock does redingtonite form in?+
What is redingtonite used for?+
Find redingtonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
