Chantalite

Chemical formula: CaAl<sub>2</sub>SiO<sub>4</sub>(OH)<sub>4</sub>

Chantalite is a very rare calcium aluminum silicate, forming small, colorless, and transparent crystals with a tetragonal habit.

## Characteristics Chantalite is a silicate mineral belonging to the group of rare minerals. It most often forms very small, but well-formed, euhedral crystals. Typical specimens are in the form of pyramidal, tetragonal dipyramids, less commonly short prisms. They are colorless and fully transparent, with a strong, vitreous luster, which gives them an appearance resembling unpolished diamonds or zircons. ## Physical Properties The Mohs hardness of chantalite is 5, which places it on par with apatite. It is a relatively brittle mineral, with good cleavage in two directions and a conchoidal fracture. Its density is approximately 2.96 g/cm³. It is characterized by a vitreous luster and a white streak. ## Colors and Varieties This mineral is colorless. No colored varieties or trade names are known. ## History and Name Chantalite was first described in 1977 by Michel Fleck, Pierre-Jacques Perroud, Zdeněk Johan, and Paul-Henri Meixner. The mineral's name honors Chantal Sarp, the wife of Swiss mineralogist Halil Sarp. Type specimens come from the Jeffrey Mine in Asbestos (now Val-des-Sources), Quebec, Canada, and are preserved in the Natural History Museum in Geneva. ## Applications Due to its extreme rarity and small crystal size, chantalite has no industrial application. It is solely an object of scientific and collector interest.

Properties

Mohs hardness
5
Luster
Vitreous
Streak
White
Density
2.96
Cleavage
Good on {001} and {100}
Fracture
Conchoidal
Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification The key diagnostic feature of chantalite is its characteristic crystallographic form – a sharp, tetragonal dipyramid. Other important features include its lack of color, transparency, vitreous luster, and specific occurrence environment (rodingites). ## Distinguishing from Similar Minerals Chantalite is sometimes confused with other colorless minerals occurring in similar parageneses. It is distinguished from colorless grossular (garnet) by its tetragonal crystal system (grossular is isometric) and lower hardness. Vesuvianite, also tetragonal, usually has a different crystal habit, higher hardness, and density. Quartz, although similar in hardness, crystallizes in the trigonal system and does not exhibit cleavage. ## Crystal Forms Chantalite forms classic, sharp, and lustrous tetragonal dipyramids. Crystals are usually single, grown on the host rock. Their size rarely exceeds 1-2 millimeters, and most specimens are submillimeter crystals.

Geological environment

## Genesis Chantalite is a product of contact metamorphism. It forms under specific conditions within rodingites – metasomatic rocks rich in calcium and aluminum, which form as a result of the interaction of hydrothermal fluids with ultramafic rocks (e.g., serpentinites, peridotites). ## Mineral Associations This mineral co-occurs with other minerals typical of rodingites, such as grossular, diopside, vesuvianite, clinochlore, and titanite. ## Localities The most important and well-known locality for chantalite, from which the best specimens originate, is the Jeffrey Mine in Val-des-Sources (formerly Asbestos), Quebec, Canada. Other confirmed localities include the Bazhenovskoye deposit in the Ural Mountains, Russia, and the area around Fuka in Okayama Prefecture, Japan.

Rarity

Very rare

For collectors

## Quality Criteria The collector's value of chantalite is determined by its rarity. Most prized are specimens with sharp, fully transparent, and undamaged crystals exceeding 1 mm in size. Rich clusters of small but perfectly formed crystals on a small rock matrix are also highly valued. A contrasting matrix or association with other well-formed minerals (e.g., green diopside) enhances the specimen's attractiveness. ## Popular Localities The vast majority of the world's best chantalite specimens come from the type locality – the now-closed Jeffrey Mine in Canada. Specimens from other localities are extremely rare on the collector's market.

Care and storage

## Cleaning Chantalite specimens should be cleaned very carefully, using a soft brush and distilled water. Due to the small size of the crystals, working under magnification is recommended. ## What to Avoid Avoid ultrasonic cleaners, which can damage crystals or cause them to detach from the matrix. The mineral is sensitive to strong acids. Due to its cleavage, it should be protected from impacts and sudden temperature changes. ## Storage The safest way to store it is to place the specimen in a closed "micromount" box, lined with soft foam, which protects it from dust and mechanical damage. It is stable and not sensitive to light.

Sources

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