Ferriphoxite
Chemical formula: [(N³⁻H₄)₂K(H₂O)][Fe³⁺(HPO₄)₂((C₂)⁶⁺O₄)]
Ferriphoxite is a hydrated iron phosphate from the phoxite group, forming microscopic, bladed crystals of white color.
Properties
- Mohs hardness
- 2-0
- Color
- colorless
- Luster
- Vitreous to pearly
- Streak
- white
- Density
- 2.14
- Cleavage
- three good cleavages ({100}, {010} and {001})
- Fracture
- Splintery
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of ferriphoxite is possible only through advanced analytical methods, such as X-ray diffraction (XRD) and chemical spectroscopy (EDS), due to its microscopic size and occurrence. Visual identification in the field or even in a collection is impossible. ## Distinguishing from Similar Minerals It can be confused with other microscopic phosphates occurring in similar environments, such as phoxite, parahopeite, or tarbuttite. Definitive differentiation requires specialized chemical and crystallographic analysis. ## Crystal Forms It forms elongated, bladed or acicular crystals, flattened along one of the axes. These crystals often combine into radial or stellate aggregates and rosettes.
Geological environment
## Genesis Ferriphoxite is a secondary mineral that crystallizes under low-temperature conditions. It forms as a result of the reaction of phosphate-rich solutions, originating from bat guano, with iron minerals present in rocks. It is a product of hydrothermal processes occurring in the late stage of mineralization. ## Mineral Associations At the type locality (Rowley Mine), it co-occurs with minerals such as wulfenite, fluorite, barite, quartz, calcite, and other rare phosphates. ## Localities The only confirmed occurrence of ferriphoxite in the world is the Rowley Mine (Rowley Cave) in the Painted Rock Mountains area, Maricopa County, Arizona, USA. This is its type locality.
Rarity
Extremely rare
For collectors
## Quality Criteria As a microscopic mineral, the collector's value of ferriphoxite depends on the quality and richness of the crystal aggregates on the rock matrix. Specimens with well-formed, radial rosettes of crystals that are clearly visible against a contrasting matrix are most prized. Association with other rare minerals from this locality is also important. ## Popular Localities The only source of specimens is the Rowley Mine (cave) in Arizona, which is world-renowned for its rare and well-crystallized secondary minerals.
Care and storage
## Cleaning Specimens should be handled with utmost care. Cleaning is not recommended due to the extreme fragility and small size of the crystals. Any attempts at mechanical or chemical cleaning may irreversibly destroy the specimen. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and sudden temperature changes. The crystals are very delicate and susceptible to mechanical damage. ## Storage Ferriphoxite specimens, usually in the form of "micromounts," should be stored exclusively in specialized, sealed perky boxes to protect them from dust, moisture, and physical damage. Vibrations and shocks should be avoided.