Eriochalcite
A variety of Minerals
What is Eriochalcite?
Copper(II) chloride is the chemical compound with the chemical formula CuCl2. This is a green blue solid, which slowly absorbs moisture to form a blue-green dihydrate. Both the anhydrous and the dihydrate forms occur naturally as the very rare minerals tolbachite and eriochalcite, respectively.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Eriochalcite 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.
Eriochalcite Localities Map
See where Eriochalcite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Composition of Eriochalcite
Anhydrous CuCl2 adopts a distorted cadmium iodide structure. In this motif, the copper centers are octahedral. Most copper(II) compounds exhibit distortions from idealized octahedral geometry due to the Jahn-Teller effect, which in this case describes the localization of one d-electron into a molecular orbital that is strongly antibonding with respect to a pair of chloride ligands. In CuCl2·2H2O, the copper again adopts a highly distorted octahedral geometry, the Cu(II) centers being surrounded by two water ligands and four chloride ligands, which bridge asymmetrically to other Cu centers. Copper(II) chloride is paramagnetic. Of historical interest, CuCl2·2H2O was used in the first electron paramagnetic resonance measurements by Yevgeny Zavoisky in 1944.
Quick Facts
Physical Properties
- Color
- Bluish green, greenish blue, yellowish tint at times.
- Hardness (Mohs)
- 2.5
- Density
- 2.55 g/cm³
Chemical Properties
- Chemical Formula
- CuCl2 · 2H2O
- Elements
- Cl, Cu, H, O
Also Known As
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Eriochalcite FAQs
How do I identify Eriochalcite?
Eriochalcite can be identified by its hardness of 2.5 on the Mohs scale, Bluish green color. Look for these key characteristics when examining specimens.
What color is Eriochalcite?
Eriochalcite typically appears in Bluish green, greenish blue, yellowish tint at times.. Color can vary depending on impurities and formation conditions.
How hard is Eriochalcite?
Eriochalcite has a hardness of 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the composition of eriochalcite of Eriochalcite?
Anhydrous CuCl2 adopts a distorted cadmium iodide structure. In this motif, the copper centers are octahedral. Most copper(II) compounds exhibit distortions from idealized octahedral geometry due to the Jahn-Teller effect, which in this case describes the localization of one d-electron into a molecular orbital that is strongly antibonding with respect to a pair of chloride ligands. In CuCl2·2H2O, the copper again adopts a highly distorted octahedral geometry, the Cu(II) centers being surrounded by two water ligands and four chloride ligands, which bridge asymmetrically to other Cu centers. Copper(II) chloride is paramagnetic. Of historical interest, CuCl2·2H2O was used in the first electron paramagnetic resonance measurements by Yevgeny Zavoisky in 1944.
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