Kaliochalcite
Chemical formula: KCu²⁺₂(S⁶⁺O₄)₂[(OH)(H₂O)]
Kaliochalcite is a rare potassium-copper sulfate, forming characteristic blue-green, tabular crystals.
Properties
- Mohs hardness
- 4
- Color
- Light green, bright grass-green or almost colourless
- Luster
- Vitreous
- Streak
- Light green
- Density
- 3.49
- Cleavage
- Good on {010}
- Fracture
- Irregular/Uneven
- Transparency
- Transparent,Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Kaliochalcite can be identified by its characteristic emerald-green to blue-green color, vitreous luster, and typical tabular crystals forming rosette-like aggregates. Its occurrence in the oxidation zones of copper deposits is also an important clue. ## Distinguishing from Similar Minerals It can be confused with other secondary copper minerals of similar color, such as brochantite, linarite, or spangolite. Distinguishing it from these minerals often requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS). Linarite usually has a more intensely blue color, and brochantite most often forms acicular crystals. ## Crystal Forms Crystals are very small, thin-tabular or bladed, often with a hexagonal outline. They typically occur as radial or rosette-like aggregates and crusts on the host rock.
Geological environment
## Genesis Kaliochalcite is a secondary mineral, forming in the oxidation (weathering) zones of hydrothermal ore deposits rich in copper. It forms as a result of reactions of sulfate-bearing solutions with copper minerals, in the presence of potassium. ## Mineral Associations It often co-occurs with other secondary sulfate and arsenate minerals. In its type locality (Jáchymov), it was found in association with gypsum, chalcanthite, brochantite, johannite, uranopilite, as well as rare sulfates like marecottite and natrozippeite. ## Localities The most important and well-documented occurrences of this very rare mineral are: - **Czech Republic** - Svornost Mine, Jáchymov, Ore Mountains (type locality). - **Germany** - "Reiche Zeche" Mine in Freiberg, Saxony. - **Greece** - Mines in the Lavrion region, Attica. - **Italy** - Mount Vesuvius, where it forms as a product of volcanic exhalations (fumaroles).
Rarity
Very rare
For collectors
## Quality Criteria The most prized specimens by collectors are those with well-formed, sharp crystals forming aesthetic, rosette-like aggregates. The intensity and purity of the emerald-green color is a key factor. Contrast with the matrix rock and the presence of rare associated minerals are also important. Due to the microscopic size of the crystals, specimens are primarily evaluated under magnification. ## Popular Localities Specimens from the type locality, Jáchymov in the Czech Republic, are most sought after by collectors specializing in mineral systematics or minerals from type localities. Material from Greek Lavrion and Italian Vesuvius is also highly valued.
Care and storage
## Cleaning Kaliochalcite specimens are extremely delicate and sensitive. Cleaning should be kept to an absolute minimum. If necessary, a very soft brush can be used to remove loose dust particles. Contact with water should be avoided, as the mineral is soluble in it. ## What to Avoid Water (both distilled and tap), all chemicals, ultrasound, and sudden temperature changes must be strictly avoided. The mineral is very soft and brittle, susceptible to mechanical damage. It should not be exposed to direct sunlight, which can cause fading or degradation. ## Storage It is recommended to store specimens in sealed, lidded "micromount" boxes, which protect against dust, moisture, and physical damage. They should ideally be kept in stable room conditions, away from heat and light sources.