Dioskouriite
Chemical formula: CaCu²⁺₄Cl₆(OH)₄·4H₂O
Dioskouriite is a very rare hydrated calcium copper hydroxychloride, forming microscopic, light green crystals in volcanic fumaroles.
Properties
- Luster
- Vitreous
- Density
- 2.75
- Cleavage
- One distinct (believed to be (100)) and one imperfect
- Fracture
- Irregular/Uneven
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of dioskouriite is practically possible only through advanced analytical methods, such as X-ray diffraction (XRD) and chemical spectroscopy (EDS/WDS). Visually, under high magnification, characteristic, small, light green tabular crystals can be observed in association with other fumarole minerals. ## Distinguishing from similar minerals It can be confused with many other green secondary copper minerals, such as atacamite, paratacamite, belloite, or the aforementioned castorite. Certain distinction from these minerals requires specialized laboratory analysis, as their physical properties and appearance at the micro scale are very similar. ## Crystal forms Dioskouriite forms very small, thin, tabular or lath-like crystals, often flattened. They usually occur as irregular clusters, rosettes, or fan-shaped aggregates on the surface of the host rock.
Geological environment
## Genesis Dioskouriite is a mineral of volcanic origin, formed by sublimation from volcanic gases in a fumarolic environment. It crystallizes in zones of high geothermal activity, where hot gases rich in chlorine, copper, and other elements react with volcanic rocks. ## Mineral associations This mineral co-occurs with other rare products of volcanic exhalations. In its type locality, it was found in association with minerals such as halite, sylvite, carnallite, mitscherlichite, sangarzonite, romanorlanite, avdoninite, eriochalcite, as well as hematite and tenorite. ## Localities The only confirmed occurrence of dioskouriite in the world is its type locality - the Arsenatnaya fumarole on Tolbachik volcano, located on the Kamchatka Peninsula in Russia.
Rarity
Extremely rare
For collectors
## Quality criteria The quality of dioskouriite specimens is primarily assessed based on the richness and aesthetics of the crystal aggregates visible under a microscope. Most valued are samples with well-formed, undamaged crystals of intense, light green color, forming visually attractive clusters. Contrast with the rock matrix and the presence of rare associated minerals are also important. ## Popular localities All known collector specimens come from a single location worldwide: the fumarole of Tolbachik volcano in Kamchatka. This makes it an extremely difficult mineral to acquire, available only on the specialized micromount mineral market.
Care and storage
## Cleaning Specimens of dioskouriite are extremely delicate and usually microscopic in size. They should not be cleaned mechanically or chemically. Any attempts at cleaning risk irreversible destruction of the mineral. Specimens should be protected from dust by storing them in sealed containers. ## What to avoid Avoid contact with water and chemicals that may dissolve or damage the delicate crystals. The mineral is sensitive to changes in temperature and humidity. It should not be heated or exposed to direct sunlight. ## Storage It is recommended to store specimens exclusively in specialized, sealed "micromount" boxes, which protect them from mechanical damage, dust, and humidity changes. Display should only occur under controlled conditions.