Nashite
Chemical formula: Na₃Ca₂(H₂O)₂₂[(V⁴⁺V⁵⁺₉)O₂₈]·2H₂O
Nashite is a very rare, hydrated sodium calcium vanadate, forming transparent, blue-green crystals and coatings.
Properties
- Mohs hardness
- 2
- Luster
- Vitreous
- Streak
- Light bluish-green
- Density
- 2.350
- Cleavage
- One good cleavage on {010}
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Key diagnostic features of nashite include its characteristic blue-green color, occurrence as small, tabular crystals forming aggregates or coatings, and very low hardness (2 on the Mohs scale). An important indicator is also its genesis – its occurrence in vanadium-rich sandy sediments. ## Distinguishing from Similar Minerals Nashite can be confused with other secondary vanadium minerals of similar color, such as pascoite, huemulite, or sherwoodite. However, pascoite has a more orange-red color. Precise differentiation from other green and blue-green vanadates (e.g., lasalite, santafeite) is extremely difficult without advanced chemical (EDS) or X-ray (XRD) analyses. ## Crystal Forms Nashite forms thin, tabular or bladed crystals, elongated along the crystallographic axis. These crystals often combine into radial or fan-shaped aggregates, and also form thin, brittle crusts and coatings on rock surfaces.
Geological environment
## Genesis Nashite is a secondary vanadium mineral that forms in the oxidation zone of uranium-vanadium deposits located in sedimentary rocks, mainly sandstones. It forms as a result of weathering and alteration of primary vanadium minerals under low temperature and pressure conditions, often in arid or semi-arid climates. ## Mineral Associations This mineral co-occurs with other secondary uranium and vanadium minerals. The most common associations include: tyuyamunite, carnotite, pascoite, huemulite, sherwoodite, as well as gypsum and montmorillonite. ## Localities Nashite is an extremely rare mineral, known from only a few localities worldwide. It was discovered and described from two localities in the USA: the Little Eva mine in Grand County, Utah, and the Saint Jude mine in San Miguel County, Colorado. These are its type localities and main source of specimens.
Rarity
Very rare
For collectors
## Quality Criteria The most prized nashite specimens are those with well-formed, transparent crystals of intense, blue-green color, forming aesthetic, radial aggregates. Due to the small size of the crystals, their quality and form are crucial, as is the contrast with the rock matrix. Specimens rich in numerous, well-defined crystalline rosettes achieve the highest value. ## Popular Localities The only significant localities for collectors are in the USA, in the Colorado Plateau region. Specimens from the Little Eva mine (Utah) and Saint Jude mine (Colorado) are considered classic and most desirable.
Care and storage
## Cleaning Nashite specimens are extremely delicate and sensitive to water. Mechanical cleaning is highly risky. If absolutely necessary, a stream of compressed air can be used to remove loose dust. Any contact with water or other liquids should be avoided. ## What to Avoid Nashite is a hydrated mineral and can undergo dehydration (loss of water) in dry air or at elevated temperatures, leading to its destruction. Contact with water, chemicals, ultrasound, and exposure to direct sunlight and heat sources must be strictly avoided. It is very soft and susceptible to scratching. ## Storage It is recommended to store specimens in sealed, transparent containers (so-called "micromount boxes"), which protect against mechanical damage and humidity fluctuations. Display should be away from light and heat sources.