Navajoite
Chemical formula: (V⁵⁺,Fe³⁺)₁₀O₂₄·12H₂O
Navajoite is a rare vanadium and iron oxide, forming dark brown to black, fibrous aggregates with a silky luster.
Properties
- Mohs hardness
- 1.5
- Color
- Dark brown
- Luster
- Silky
- Streak
- Light brown
- Density
- 2.56
- Cleavage
- Perfect on {010}
- Fracture
- Fibrous
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Key diagnostic features of navajoite include its occurrence as dark brown, fibrous or felted aggregates, very low hardness (can be scratched with a fingernail), and silky luster. Its genesis, associated with the oxidation zones of uranium-vanadium deposits, is also characteristic. ## Distinguishing from Similar Minerals Navajoite can be confused with other vanadium oxides of similar appearance, such as corvusite or doloresite. Differentiation often requires advanced analytical methods (XRD, EDS). It is distinguished from goethite or other manganese oxides by its lower hardness and specific environment of occurrence. ## Crystal Forms This mineral forms microscopic, platy or acicular crystals that combine into dense, felted or radial aggregates. Less commonly, it occurs as coatings and crusts on other minerals or host rock.
Geological environment
## Genesis Navajoite is a secondary mineral, formed in the oxidation zones of uranium-vanadium deposits hosted in sandstones. It forms as a result of weathering and alteration of primary vanadium minerals, often under low pH conditions and in the presence of groundwater. ## Mineral Associations It most commonly co-occurs with other vanadium minerals, such as corvusite, hewettite, tyuyamunite, carnotite, as well as with montmorillonite, gypsum, and clay minerals. It often forms pseudomorphs after other minerals. ## Localities The most important and best-documented occurrences of navajoite are found on the Colorado Plateau in the USA, particularly in Arizona (Monument No. 2 mine in Apache County – type locality) and Utah. It is also known from several localities in New Mexico.
Rarity
Rare
For collectors
## Quality Criteria Specimens with well-formed, rich fibrous aggregates covering a significant area of the rock matrix are most valued by collectors. The contrast of dark brown navajoite fibers with lighter sandstone enhances visual appeal. The abundance of material and the absence of damage to delicate structures are also important. ## Popular Localities By far the most sought-after specimens come from the classic locality at the Monument No. 2 mine in Arizona, USA. Specimens from this location are considered exemplary for the species.
Care and storage
## Cleaning Navajoite is extremely delicate and soft. Any mechanical cleaning, including the use of brushes, should be avoided. It should also not be washed with water, as it is a hydrated mineral and may undergo changes. The safest method is to carefully remove dust using a photographic air blower or compressed air from a distance. ## What to Avoid Contact with water, chemicals, acids, and detergents must be absolutely avoided. The mineral is very soft, susceptible to scratches and disintegration. It should be protected from shocks, drops, and pressure. Prolonged exposure to direct sunlight or high temperatures can lead to dehydration and damage to the specimen. ## Storage Navajoite specimens should be stored in stable conditions, in closed, padded boxes or display cases, to protect them from dust, moisture, and mechanical damage. It is best to store it away from other, harder minerals.