Szomolnokite is a secondary sulfate mineral that typically forms as efflorescent crusts or granular aggregates in the oxidation zones of iron-bearing sulfide deposits. It is often pale yellow or brownish in color and is notorious for being unstable in humid environments, where it may hydrate into other iron sulfate species. Collectors should store this mineral in a dry, sealed container to prevent degradation.
Is this szomolnokite?
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 szomolnokite with a known reference. Szomolnokite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, bluish, colorless, yellow brown, light blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: crusts, granular, fibrous.
Often confused with
Szomolnokite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside szomolnokite
Minerals reported to co-occur with szomolnokite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeSO₄·H₂O
- Mohs hardness
- 2.5
- Density
- 3.03-3.07 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent when unoxidized
- Crystal system
- Monoclinic
- Crystal habit
- Crusts, granular, fibrous
- Cleavage
- Indistinct
- Rarity
- Uncommon
- Uses
- Collector, Scientific reference
- Host rock
- An uncommon secondary mineral formed in pyrite-rich oxidized sulfide deposits, typically under highly acid and arid conditions
Where rockhounds find szomolnokite
Classic worldwide localities
- Tintic Standard mine, near Dividend, East Tintic district, Utah Co., USA
- Bisbee, Cochise Co. and in the Magma mine, Pinal Co., Arizona, USA
- Goldstrike mine, Lynn district, Eureka Co., Nevada, USA
- Island Mountain mine, Trinity Co., California, USA
- Smolník (Szomolnok), 16 km northeast of Rožňava, Slovakia
- Valachov Hill, near Skřivaň, and at Kladno, Czech Republic
Field-hunting tip
Where it forms: An uncommon secondary mineral formed in pyrite-rich oxidized sulfide deposits, typically under highly acid and arid conditions. If you start seeing rhomboclase, halotrichite, fibroferrite in float, you are in the right ground. Typical habit: crusts, granular, fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify szomolnokite?+
Where is szomolnokite found?+
What rocks look like szomolnokite?+
What minerals are found with szomolnokite?+
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What is szomolnokite used for?+
Find szomolnokite on the map
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