Windmountainite

Chemical formula: ◻Fe³⁺₂Mg₂Si₈O₂₀(OH)₂·8H₂O

Windmountainite is a very rare, fibrous mineral of the palygorskite group, characterized by its orange-brown color, discovered in the Wind Mountains in New Mexico.

## Characteristics Windmountainite is a hydrated iron and magnesium silicate, belonging to the palygorskite group. It forms felted, flexible fibrous aggregates that can reach up to 1 cm in length. Its appearance is very distinctive due to its intense, orange-brown color and fibrous structure. It is a translucent mineral with a silky luster. ## Physical Properties This mineral is very soft, with a Mohs hardness of only 2. It is relatively light, with a density of 2.51 g/cm³. It is predicted to have two good cleavage planes, and its fracture is splintery, which is typical for minerals with a fibrous structure. The streak left on a plate is orange-brown. ## Colors and Varieties Windmountainite occurs in a uniform, orange-brown color. No color or commercial varieties have been distinguished. ## History and Name The mineral's name comes directly from its discovery location – Wind Mountain in the Cornudas Mountains range, Otero County, New Mexico, USA. This is the only known occurrence of this mineral in the world (type locality). ## Applications Due to its extreme rarity, windmountainite has no industrial applications. It is solely an object of scientific and collecting interest for specialized collectors of rare minerals.

Properties

Mohs hardness
2
Luster
Silky
Streak
Orange-brown
Density
2.51
Cleavage
Two good cleavages (predicted) on {110}
Fracture
Splintery
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Windmountainite can be identified by its unique combination of features: orange-brown color, distinctly fibrous, often felted structure, very low hardness (2 on the Mohs scale), and silky luster. The flexibility of its fibers is also characteristic. ## Distinguishing from Similar Minerals It can be confused with other fibrous minerals from the palygorskite or sepiolite group, but its intense orange-brown color is a distinguishing feature. Final confirmation of identity requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis. ## Crystal Forms This mineral forms aggregates of thin, flexible fibers that are usually felted and tangled. Individual, well-formed crystals are not observed.

Geological environment

## Genesis Windmountainite forms under hydrothermal conditions in vugs and fissures of phonolite, which is an alkaline extrusive rock. Its crystallization occurs at relatively low temperatures from solutions rich in silica, magnesium, and iron. ## Mineral Associations This mineral co-occurs with other rare minerals found at this locality, such as analcime, nepheline, sanidine, aegirine, as well as rare silicates like tuperssuatsiaite. ## Localities The only confirmed occurrence of windmountainite in the world is its type locality: Wind Mountain in the Cornudas Mountains range, Otero County, New Mexico, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a windmountainite specimen is assessed based on the abundance and preservation of its fibrous aggregates. Specimens with distinct, dense fibrous aggregates of intense, orange-brown color, contrasting with the host rock (phonolite), are most valued. Due to the nature of the mineral, clarity and transparency are not key criteria. ## Popular Localities The only source of specimens is the type locality in New Mexico, USA. Material from this location is extremely difficult to acquire and appears on the collector's market sporadically.

Care and storage

## Cleaning Windmountainite specimens are extremely delicate and fragile. They should only be cleaned using compressed air to remove dust. Any contact with water or chemicals is absolutely inadvisable. ## What to Avoid Avoid contact with water, acids, detergents, and all other liquids. The mineral is very soft, susceptible to scratches and mechanical damage. Protect it from vibrations, impacts, and abrasion. Do not heat it or expose it to temperature changes. ## Storage Specimens should be stored in stable conditions, in a closed, padded "micromount" box to protect them from dust, moisture, and physical damage. It is not suitable for display outside of a specialized protective container.

External references

Sources

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