Rhomboclase
A variety of Minerals
What is Rhomboclase?
Rhomboclase is an acidic iron sulfate mineral with a formula reported as H5FeO2(SO4)2·2(H2O) or HFe(SO4)2·4(H2O). It crystallizes in the orthorhombic system and typically occurs as tabular crystals with a rhombic outline. It occurs as transparent colorless, blue, green, yellow or grey crystals with a vitreous to pearly luster. Rhomboclase forms within the oxidizing environment of pyrite rich ore deposits and is reported as a post mine mineral of arid regions. It was first described in 1888 for an occurrence in Slovakia and was named from Latin, rhombus, rhomb, and Greek klasis, to break, for its crystal form and perfect basal cleavage.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Rhomboclase before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Rhomboclase Localities Map
See where Rhomboclase is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Color
- Blue, colourless, white, yellow, light green, grey; colourless in transmitted light
- Hardness (Mohs)
- 2
- Density
- 2.21 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- (H5O2)Fe3+(SO4)2 · 2H2O May contain minor As.
- Elements
- Fe, H, O, S
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Rhomboclase FAQs
How do I identify Rhomboclase?
Rhomboclase can be identified by its hardness of 2 on the Mohs scale, Blue color. Look for these key characteristics when examining specimens.
What color is Rhomboclase?
Rhomboclase typically appears in Blue, colourless, white, yellow, light green, grey; colourless in transmitted light. Color can vary depending on impurities and formation conditions.
How hard is Rhomboclase?
Rhomboclase has a hardness of 2 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
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