Belloite

Chemical formula: Cu<sup>2+</sup>(OH)Cl

Belloite is an extremely rare copper, potassium, and chlorine mineral, occurring as small, green crystals in volcanic fumaroles.

## Characteristics Belloite forms small, prismatic crystals, usually not exceeding 0.2 mm in length. It is characterized by a vivid green color and a vitreous luster. It is a transparent mineral. It occurs as coatings and small crystalline aggregates on volcanic rocks. ## Physical Properties Due to its extreme rarity and small crystal size, many physical properties, such as hardness, density, or fracture, have not been precisely determined. The luster is vitreous, and the mineral is transparent. ## Colors and Varieties It occurs in a uniform green color. No color varieties or commercial varieties are distinguished. ## History and Name The mineral was first described in 1998 by S. A. Williams and M. Duggan. Its name honors the Italian mineral collector, Francesco Bellone (b. 1945), who found the first specimens. The type locality is the "Atrio del Cavallo" fumarole on Mount Vesuvius in Italy. ## Uses Belloite has no industrial applications. It is of purely scientific and collector's interest as an extremely rare mineral.

Properties

Luster
Vitreous
Streak
Light green
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification is possible almost exclusively based on chemical (EDS) and crystallographic (XRD) analysis due to the small size of the crystals and its occurrence in paragenesis with other copper chlorides. ## Distinguishing from Similar Minerals It can be confused with other green fumarole products, such as eriochalcite (CuCl₂·2H₂O) or melanothallite (Cu₂OCl₂). Differentiation requires advanced research methods. ## Crystal Forms It forms elongated, prismatic crystals, often grouped into small aggregates.

Geological environment

## Genesis It is a mineral of fumarolic origin. It forms as a result of the exhalation of volcanic gases rich in chlorine, potassium, and copper, which crystallize at high temperatures on the surface of volcanic rocks. ## Mineral Associations It co-occurs with other fumarole minerals of Mount Vesuvius, such as eriochalcite, melanothallite, and sylvite. ## Localities The only confirmed locality in the world is its type locality – the "Atrio del Cavallo" fumarole on Mount Vesuvius, in the Campania region of Italy.

Rarity

Extremely rare

For collectors

## Quality Criteria In the case of such a rare mineral, the main criterion is the mere confirmation of its presence on a fragment of the host rock. Well-formed, as large as possible crystals and a rich association with other rare minerals are an additional advantage. ## Popular Localities The only source of specimens is Mount Vesuvius in Italy.

Care and storage

## Cleaning Belloite specimens are extremely delicate and small. They should not be cleaned mechanically or chemically. Any attempts at cleaning risk destroying the mineral. ## What to Avoid Contact with water and chemicals should be avoided, as it is likely soluble as a chloride. It is sensitive to changes in temperature and humidity. It should be protected from shocks and abrasion. ## Storage It requires storage under stable conditions, preferably in a sealed, closed "micromount" box, protecting it from dust, moisture, and mechanical damage.

External references

Sources

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