Lasalite

Chemical formula: [Mg(H₂O)₆]₂Na₂[V⁵⁺₁₀O₂₈](H₂O)₈

Lasalite is a very rare, hydrated sodium and magnesium vanadate, forming delicate, yellow coatings and crystals.

## Characteristics Lasalite is a mineral from the decavanadate group, belonging to the pascoite family. It occurs as small, tabular or bladed crystals, often forming rosetted aggregates, as well as coatings and efflorescences. Its crystals are typically transparent and have an intense, yellow to yellowish-orange color. ## Physical Properties This mineral is extremely soft, with a Mohs hardness of only 1, meaning it can be scratched with a fingernail. It is also very light, with a density of approximately 2.38 g/cm³. The crystals exhibit a vitreous luster. ## Colors and Varieties Lasalite occurs in uniform, bright colors ranging from yellow to yellowish-orange. No color varieties or commercial varieties are distinguished. ## History and Name The mineral's name comes from its discovery location – it was found in the La Sal Mountains region (La Sal Mountains) in San Juan County, Utah, USA. It was described as a new mineral in 1983. ## Uses Due to its rarity, small size, and extreme fragility, lasalite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or vanadium minerals.

Properties

Mohs hardness
1
Luster
Vitreous
Streak
Yellow
Density
2.38
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Lasalite can be identified by its characteristic bright yellow color, very low hardness (1 on the Mohs scale), and typical forms of occurrence – small, tabular crystals forming aggregates or coatings. Its occurrence is limited to the oxidation zones of uranium-vanadium deposits. ## Distinguishing from Similar Minerals It can be confused with other secondary vanadium minerals, such as carnotite, tyuyamunite, or pascoite. It differs from carnotite and tyuyamunite by its lack of radioactivity. From pascoite, which is orange-red, it usually differs by a lighter, more yellow hue. However, definitive differentiation often requires advanced chemical analysis. ## Crystal Forms Lasalite crystals are most often tabular or bladed, grouped into rosetted or radial aggregates. It also forms thin coatings and powdery efflorescences on host rocks, mainly on sandstones.

Geological environment

## Genesis Lasalite is a secondary mineral formed in the oxidation zones of uranium-vanadium deposits that occur in sandstones. It forms in arid climates as a result of the weathering processes of primary vanadium minerals. It is an unstable mineral that can undergo transformations due to changes in humidity. ## Mineral Associations It most commonly co-occurs with other secondary vanadium minerals, such as hewettite, metahewettite, pascoite, as well as gypsum and montmorillonite. ## Localities The most important and type locality for lasalite is the Vanadium Queen mine in the La Sal Creek district, San Juan County, Utah, USA. This is the main locality from which specimens of this mineral originate.

Rarity

Very rare

For collectors

## Quality Criteria The most prized lasalite specimens are those with well-formed, macroscopic crystals forming rich, rosetted aggregates on a small rock matrix. The intensity and purity of the yellow color also increase the value of the specimen. Due to its rarity, even rich coatings without distinct crystals are sought after by collectors. ## Popular Localities The only significant source of collector specimens is its type locality – the Vanadium Queen mine in Utah, USA. Specimens from this location are the standard for this species.

Care and storage

## Cleaning Lasalite is extremely delicate and water-soluble. It must absolutely not be cleaned with water. The only permissible method is very careful dust removal using a soft brush or a photographic air blower, without touching the crystal surfaces. ## What to Avoid Contact with water, any chemicals, and even humid air, which can cause its decomposition, should be avoided. The mineral is very soft, so it must be protected from even the slightest abrasions and shocks. Prolonged exposure to sunlight can cause fading. ## Storage Lasalite specimens require storage in dry conditions, preferably in a sealed, closed "perky box" away from sources of moisture and light. Due to its fragility, it is not suitable for open display.

External references

Sources

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