Kvanefjeldite

Chemical formula: Na<sub>4</sub>CaSi<sub>6</sub>O<sub>14</sub>(OH)<sub>2</sub>

Kvanefjeldite is a rare, colorless or white sodium calcium silicate, occurring as fibrous or bladed aggregates.

## Characteristics Kvanefjeldite is a rare mineral from the silicate group, chemically a hydrated sodium calcium silicate. It typically forms small, fibrous or bladed aggregates, which can be colorless, white, or grayish. Crystals are very small, often microscopic, and rarely exceed 1 mm in length. This mineral is brittle. ## Physical Properties Kvanefjeldite has a hardness of approximately 5.5 on the Mohs scale. It has a vitreous luster and is transparent to translucent. Its density is about 2.61 g/cm³. ## History and Name The mineral's name comes from its discovery locality – the Kvanefjeld plateau in the Ilímaussaq alkaline complex in Greenland. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1982. The discoverers were O. V. Petersen, J. G. Rønsbo, and E. S. Leonardsen.

Properties

Mohs hardness
5.5
Luster
Vitreous
Streak
White
Density
2.61
Cleavage
Perfect on {010}, good on {100}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Kvanefjeldite is difficult to identify visually without specialized equipment. Its characteristic features include its occurrence as fine, fibrous or bladed aggregates with a vitreous luster. It often requires chemical analysis (EDS) or X-ray diffraction (XRD) for certain identification. ## Distinguishing from Similar Minerals It can be confused with other white, fibrous silicates found in the same environment, such as ussingite, tugtupite, or natrolite. Differentiation requires advanced analytical methods, as macroscopic features are often ambiguous. ## Crystal Forms It forms elongated, bladed or acicular crystals, usually grouped into radial or tangled aggregates. Single, well-formed crystals are extremely rare.

Geological environment

## Genesis Kvanefjeldite is a hydrothermal mineral. It forms in the late stages of crystallization within nepheline syenites and associated pegmatites. It occurs in vugs and fractures within these rocks. ## Mineral Associations This mineral co-occurs with other rare alkaline minerals, such as steenstrupine-(Ce), ussingite, tugtupite, lueshite, as well as more common ones like albite, microcline, aegirine, nepheline, and sodalite. ## Localities The only confirmed and well-described locality for kvanefjeldite in the world is its type locality – the Kvanefjeld plateau in the Ilímaussaq intrusive complex, South Greenland.

Rarity

Very rare

For collectors

## Quality Criteria As a "micromount" type mineral, its collector value primarily depends on the richness of the aggregates and the aesthetic combination with other rare minerals from this locality. Specimens with clearly visible, though small, crystalline aggregates on a contrasting rock matrix are most prized. Purity and transparency are not key criteria due to the nature of the mineral. ## Popular Localities The only source of kvanefjeldite specimens is the Ilímaussaq complex in Greenland. Material from this locality is highly valued by collectors specializing in rare minerals and alkaline rock minerals.

Care and storage

## Cleaning Kvanefjeldite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its rarity and delicate nature, washing in water, and especially using ultrasonics, should be avoided. ## What to Avoid Contact with acids and other chemicals that can damage the mineral should be avoided. It is sensitive to sudden temperature changes. As a mineral with a delicate structure, it is susceptible to mechanical damage. ## Storage It is recommended to store specimens in stable conditions, in sealed "micromount" boxes, to protect them from dust, moisture, and physical damage. Exposure to direct sunlight should be avoided.

Sources

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