Posnjakite
A variety of Minerals
What is Posnjakite?
Posnjakite is a hydrated copper sulfate mineral. It was discovered in the Tungsten deposit of Nura-Taldy in Karaganda Region in Kazakhstan and described in 1967 by Aleksandr Ivanovich Komkov (1926–1987) and Yevgenii Ivanovich Nefedov (1910–1976) and named after geochemist Eugene Valdemar Posnjak (1888–1949).
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Posnjakite 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.
Key Characteristics
Formation of Posnjakite
Posnjakite is an uncommon but widespread secondary mineral in the oxidised zone of copper sulfide deposits, which may be of post-mine formation. It is associated with brochantite, langite, devilline, serpierite, woodwardite, wroewolfeite, aurichalcite, azurite, malachite and chalcopyrite.
Quick Facts
Physical Properties
- Color
- Sky-blue to dark-blue, may be slightly greenish-blue.
- Hardness (Mohs)
- 2 - 3
- Rock tumbling
- Not recommended
- Density
- 3.35 g/cm³
- Streak
- Pale-blue.
Chemical Properties
- Chemical Formula
- Cu4(SO4)(OH)6 · H2O
- Elements
- Cu, H, O, S
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Posnjakite FAQs
How do I identify Posnjakite?
Posnjakite can be identified by its hardness of 2 - 3 on the Mohs scale, Sky-blue to dark-blue color. Look for these key characteristics when examining specimens.
What color is Posnjakite?
Posnjakite typically appears in Sky-blue to dark-blue, may be slightly greenish-blue.. Color can vary depending on impurities and formation conditions.
How hard is Posnjakite?
Posnjakite has a hardness of 2 - 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the formation of posnjakite of Posnjakite?
Posnjakite is an uncommon but widespread secondary mineral in the oxidised zone of copper sulfide deposits, which may be of post-mine formation. It is associated with brochantite, langite, devilline, serpierite, woodwardite, wroewolfeite, aurichalcite, azurite, malachite and chalcopyrite.
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