Cubo-ice

Chemical formula: H<sub>₂</sub>O

Cubo-ice, scientifically known as Ice Ic, is a rare, metastable variety of ice crystallizing in the cubic system, found in the upper layers of the atmosphere.

## Characteristics Cubo-ice, or ice with a cubic structure, scientifically designated as Ice Ic, is one of several known polymorphic varieties of ice. Visually, it is indistinguishable from common hexagonal ice (Ice Ih) – it forms colorless, transparent crystals. Its uniqueness lies in its internal atomic structure, where water molecules are arranged in a cubic, rather than hexagonal, crystal lattice. It is a metastable phase, meaning that under certain conditions, it spontaneously and irreversibly transforms into the more stable Ice Ih. ## Physical Properties Its hardness is very low, similar to that of ordinary ice, approximately 1.5 on the Mohs scale. It exhibits a vitreous luster and is completely transparent if free of impurities or gas bubbles. Its density is slightly greater than that of hexagonal ice. It does not show cleavage, and its fracture is conchoidal. ## Colors and Varieties Cubo-ice is colorless. It is itself a polymorphic variety of ice (H₂O) and does not form other colored or commercial varieties. ## History and Name The name "Cubo-ice" is a descriptive term, derived from the English word *cubic*, referring to its crystallographic system. In scientific nomenclature, the designation Ice Ic is used. Its existence was first theoretically predicted and then confirmed under laboratory conditions by the condensation of water vapor at very low temperatures or by changing the pressure of other ice phases. Its presence in nature has been confirmed in the upper, cold layers of the atmosphere.

Properties

Mohs hardness: 1.5
Luster: Vitreous
Streak: White
Cleavage: None
Fracture: Conchoidal
Transparency: Transparent
Crystal system: Cubic

Diagnostic features

## Identification Identifying Cubo-ice based on visual characteristics is impossible, as it looks identical to ordinary ice. The only reliable method of identification is to analyze its crystal structure using laboratory techniques, such as X-ray diffraction (XRD) or neutron diffraction, which will confirm its cubic crystallographic system. ## Distinguishing from Similar Minerals The only similar mineral is common hexagonal ice (Ice Ih). The difference lies solely in the crystal symmetry at the atomic level (cubic vs. hexagonal) and cannot be determined without specialized equipment. ## Crystal Forms It forms microscopic crystals, often in the shape of octahedra, cubes, or as dendritic and skeletal aggregates.

Geological environment

## Genesis Cubo-ice forms naturally in the upper layers of the Earth's atmosphere (troposphere and stratosphere) as a result of water vapor condensation at temperatures from -80°C to -120°C. In laboratory conditions, it can be obtained by depositing water vapor onto a cold substrate or by decompressing high-pressure ice phases at low temperatures. ## Mineral Associations As a phase occurring in the atmosphere, it does not form associations with other minerals in a geological sense. It is a component of some high clouds, such as cirrus clouds. ## Localities Its only natural environment is the upper layers of the Earth's atmosphere. It is not found on the planet's surface in any specific geographical location.

Rarity

Extremely rare

For collectors

## Quality Criteria Cubo-ice is not of interest to mineral collectors because it cannot be acquired or stored outside of a specialized laboratory. Its value is purely scientific. ## Market Prices This mineral is not traded commercially. ## Popular Localities No localities available for collectors.

Care and storage

## Cleaning Cubo-ice is not a collectible mineral and does not occur under conditions that would allow for its collection and cleaning. ## What to Avoid This mineral is stable only at very low temperatures, below approximately -73°C (200 K). Above this temperature, it undergoes rapid and irreversible transformation into common hexagonal ice (Ice Ih). It is extremely sensitive to heat. ## Storage Storing Cubo-ice is only possible under specialized laboratory conditions, with cryogenic cooling. It cannot be stored in home conditions or as part of a typical mineral collection.

Sources

IMA Mineral List (CNMNC)