Clinobehoite

Chemical formula: Be(OH)<sub>₂</sub>

Clinobehite is a rare polymorph of behite, a beryllium hydroxide, forming tiny, colorless or white tabular crystals.

## Characteristics Clinobehite is a rare mineral from the hydroxide group, being a monoclinic polymorph of behite. It occurs as very small, tabular or platy crystals, usually not exceeding 1 mm in length. The crystals are colorless to white and transparent. Due to its small size and rarity, it is a mineral of interest mainly to specialized collectors and scientists. ## Physical Properties Clinobehite crystals exhibit a vitreous luster. This mineral is relatively soft, with a Mohs hardness of about 3. It is transparent, and its density, calculated based on the formula and cell parameters, is 1.92 g/cm³. ## Colors and Varieties Clinobehite is usually colorless, less often white. No colored or commercial varieties have been identified. ## History and Name The mineral's name refers to its monoclinic symmetry and its chemical composition, which is identical to behite. It was approved as a new mineral by the International Mineralogical Association (IMA) in 1962. It was described based on material from the Ilímaussaq complex in southern Greenland. ## Uses Clinobehite has no industrial application. Its significance is purely scientific and collectible.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: White
Density: 1.92
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identifying clinobehite is extremely difficult without advanced research methods. Preliminary identification is based on observing tiny, colorless, tabular crystals with a vitreous luster in a characteristic geological environment (nepheline-syenite pegmatites). Definitive identification requires X-ray diffraction (XRD) or chemical analysis. ## Distinguishing from Similar Minerals Clinobehite is visually indistinguishable from its orthorhombic polymorph, **behite**. Distinguishing these two minerals is only possible using X-ray diffraction. It can also be confused with other colorless, fine-grained secondary minerals found in the same environment, such as natrolite or analcime, from which it differs in crystal habit and physical properties, but in practice, this requires laboratory analysis. ## Crystal Forms It forms very small, flattened, tabular crystals with a hexagonal outline, elongated along one of the crystallographic axes. Crystals often occur in small groups and aggregates.

Geological environment

## Genesis Clinobehite is a secondary mineral, formed by hydrothermal processes in the late stages of crystallization of pegmatites associated with nepheline syenites. It forms in rock cavities and fissures, often as an alteration product of beryllium minerals, such as chkalovite. ## Mineral Associations This mineral co-occurs with other rare minerals of alkaline pegmatites. It is most commonly associated with analcime, natrolite, tugtupite, chkalovite, sorensenite, and also its polymorph - behite. ## Localities The most important and classic locality for clinobehite is the Ilímaussaq alkaline complex in Greenland, from where the best-formed specimens originate. It is also known from the Kola Peninsula in Russia, from the Khibiny and Lovozero massifs, where it occurs under similar geological conditions.

Rarity

Very rare

For collectors

## Quality Criteria Due to the microscopic nature of the mineral, the main criterion for evaluation is the quality and abundance of crystals on the rock matrix. Specimens with well-formed, sharp, transparent crystals forming rich groups are most valued. Association with other rare minerals is also important, as it increases the scientific and aesthetic value of the specimen. ## Popular Localities Specimens from the type locality – the Ilímaussaq complex in Greenland – are by far the most valued and sought after by collectors specializing in microminerals.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Due to the small size and delicacy of the crystals, wet cleaning, especially with ultrasound, is not recommended. ## What to Avoid Avoid contact with acids and other aggressive chemicals. The crystals are brittle and susceptible to mechanical damage. They should not be subjected to sudden temperature changes. ## Storage Clinobehite specimens, due to their microscopic size, are best stored in specialized micromount boxes that protect them from dust, moisture, and mechanical damage. Avoid exposure to direct sunlight, although its light sensitivity is not known.

Sources

IMA Mineral List (CNMNC)