Georgbokiite
Chemical formula: Cu²⁺₅O₂(Se⁴⁺O₃)₂Cl₂
Georgbokiite is a very rare copper selenite, forming dark green to black, tabular crystals with a metallic luster.
Properties
- Mohs hardness
- 4
- Color
- Chestnut-brown to dark brown.
- Luster
- Vitreous , Adamantine
- Streak
- Yellowish brown
- Density
- 0
- Cleavage
- {100} and {010}
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Georgbokiite is identified by its unique occurrence environment (volcanic exhalation products), characteristic form of thin, tabular crystals, dark green to black color, and strong, metallic luster. Due to the microscopic size of the crystals, definitive identification requires advanced analytical methods such as X-ray diffraction (XRD) or chemical microanalysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other rare copper selenites found in the same environment, such as chloromenite, sofiite, or ilinskite. Distinguishing them with the naked eye is practically impossible and requires specialized laboratory tests. From more common copper minerals, such as malachite or tenorite, it differs in crystal form, significantly stronger luster, and specific genesis. ## Crystal Forms It forms very small, thin, tabular crystals with hexagonal or octagonal outlines. These crystals often combine into rosette-like, radial, or chaotic aggregates, and also form thin coatings on the rock surface.
Geological environment
## Genesis Georgbokiite is a fumarolic mineral. It forms as a result of the reaction of hot volcanic gases (exhalations) with surrounding volcanic rocks. It crystallizes in zones with temperatures of 150-250°C, precipitating directly from the gas phase on the surface of basaltic lava. ## Mineral Associations This mineral co-occurs with other rare products of volcanic exhalations, such as hematite, tenorite, anglesite, sofiite, ilinskite, chloromenite, cotunnite, halite, and sylvite. ## Localities The only confirmed and type locality for georgbokiite in the world is the fumaroles of the second cinder cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption on Kamchatka, Russia.
Rarity
Very rare
For collectors
## Quality Criteria The quality of a georgbokiite specimen is determined by the abundance and development of crystals on the rock matrix. Specimens with clearly visible, sharp, lustrous crystals forming dense aggregates are most valued. The contrast of dark green crystals with a lighter host rock also enhances visual appeal. Due to the microscopic nature of the mineral, the quality of the specimen when viewed under magnification is crucial.
Care and storage
## Cleaning Due to its extreme rarity and delicacy, mechanical cleaning is highly inadvisable. If absolutely necessary, compressed air (from a safe distance) can be used to remove loose dust particles. Contact with water and any chemicals should be avoided. ## What to Avoid Contact with water, acids, detergents, and other chemicals that could damage or destroy the mineral must be strictly avoided. Georgbokiite is brittle, so it should be protected from impacts, vibrations, and abrasion. It should not be heated or exposed to sudden temperature changes. ## Storage Georgbokiite specimens should be stored in stable conditions, in a closed, padded "micromount" box, protecting them from dust, moisture, and mechanical damage. Display should only take place in enclosed display cases.