Quenstedtite is a rare hydrated iron sulfate mineral typically found as a secondary product in the oxidized zones of ore deposits. It is known for its distinct pale violet color, though it is highly soluble and must be kept away from humidity to prevent dehydration or degradation.
Is this quenstedtite?
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 quenstedtite with a known reference. Quenstedtite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light violet blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, light violet, red violet.
- 5Look at form & habitCrystal system: triclinic. Typical habit: euhedral crystals, granular.
Often confused with
Quenstedtite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Quenstedtite leaves light violet blue, Copiapite leaves pale yellow; luster reads vitreous on Quenstedtite and pearly on {010} on Copiapite.
How to tell apart: Streak differs, so Quenstedtite leaves light violet blue, Coquimbite leaves white.
Often found alongside quenstedtite
Minerals reported to co-occur with quenstedtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂(SO₄)₃·11H₂O
- Mohs hardness
- 2.5
- Density
- 2.11-2.15 g/cm³
- Colors
- Streak
- Light violet blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Euhedral crystals, granular
- Cleavage
- Perfect on {010}; good on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon mineral formed in the oxidized zone of pyrite-rich mineral deposits especially in arid regions
Where rockhounds find quenstedtite
Classic worldwide localities
- Sulphur Hole prospect, near Borate, about 10 km northeast of Yermo, Calico Mountains, San Bernardino Co., California, USA
- Tierra Amarilla, southeast of Copiapó, Atacama, and at Alcaparrosa, near Cerritos Bayos, southwest of Calama, Antofagasta, Chile
- Baňská Štiavnica (Schemnitz), Slovakia
- Richelsdorfer Mountains, Hesse, Germany
- Dyakhtardakh cassiterite–sulfide deposit, northeastern Sakha, Russia
Field-hunting tip
Where it forms: An uncommon mineral formed in the oxidized zone of pyrite-rich mineral deposits especially in arid regions. If you start seeing coquimbite, copiapite, römerite in float, you are in the right ground. Typical habit: euhedral crystals, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify quenstedtite?+
Where is quenstedtite found?+
What rocks look like quenstedtite?+
What minerals are found with quenstedtite?+
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What is quenstedtite used for?+
Find quenstedtite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
