Fontarnauite
A variety of Minerals
What is Fontarnauite?
Fontarnauite is a relatively recently described, rare sulfate, borate mineral with the chemical formula (Na,K)2(Sr,Ca)(SO4)[B5O8(OH)]·2H2O. It is found in an evaporite boron deposit. It coexists with other evaporite boron minerals, especially probertite. It is monoclinic, crystallizing in the space group P21/c. It was named for Ramon Fontarnau i Griera, a materials scientist of the University of Barcelona.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Fontarnauite 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.
Quick Facts
Physical Properties
- Color
- colorless to light brown
- Hardness (Mohs)
- 2.5 - 3
- Rock tumbling
- Not recommended
- Density
- 2.533 g/cm³
- Streak
- white
Chemical Properties
- Chemical Formula
- (Na,K)2(Sr,Ca) (SO4)[B5O8(OH)]·2H2O
- Elements
- B, Ca, H, K, Na, O, S, Sr
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Fontarnauite FAQs
How do I identify Fontarnauite?
Fontarnauite can be identified by its hardness of 2.5 - 3 on the Mohs scale, colorless to light brown color. Look for these key characteristics when examining specimens.
What color is Fontarnauite?
Fontarnauite typically appears in colorless to light brown. Color can vary depending on impurities and formation conditions.
How hard is Fontarnauite?
Fontarnauite has a hardness of 2.5 - 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
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