Aravaipaite
Chemical formula: Pb<sup>2+</sup><sub>3</sub>AlF<sub>9</sub>·H<sub>2</sub>O
This is a hydrated lead and aluminum fluoride, forming colorless, bladed crystals with a pearly luster.
Properties
- Mohs hardness
- 2
- Luster
- Pearly
- Streak
- White
- Density
- 5.85
- Cleavage
- Perfect on {100}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
Diagnostic features
## Identification Aravaipaite can be identified by its characteristic, colorless, bladed crystals forming radial aggregates. Key features include a pearly luster, very low hardness (2 on the Mohs scale), and perfect unidirectional cleavage, which causes crystals to easily separate into thin lamellae. It reacts with acids. ## Distinguishing from Similar Minerals It can be confused with other colorless secondary minerals, such as gypsum or talc, but it is distinguished from them by its significantly higher density (it is noticeably heavier). It is distinguished from mica by its crystal habit and occurrence environment. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Crystals are tabular or bladed, elongated and flattened. They usually form fan-shaped, radial, or spherulitic aggregates. They rarely occur as single, isolated crystals.
Geological environment
## Genesis Aravaipaite is a secondary mineral, forming in the oxidation zones (gossans) of polymetallic deposits, especially those rich in lead and fluorine. It forms as a result of the action of acidic, fluorine-rich solutions on primary lead-bearing minerals, under low-temperature conditions. ## Mineral Associations In its type locality (Grand Reef Mine), it co-occurs with anglesite, galena, quartz, fluorite, cerussite, linarite, as well as other rare secondary minerals such as boleite, pseudoboleite, and leadhillite. ## Localities This is an extremely rare mineral. Besides the type locality at the Grand Reef Mine in Arizona (USA), its occurrence has been confirmed in only a few other places worldwide, including the Clara Mine in the Black Forest (Germany) and the zinc-lead ore deposit in Lavrion, Greece.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of an aravaipaite specimen primarily depends on the richness and aesthetics of the crystal aggregates. Most valued are specimens with clearly formed, radial or fan-shaped clusters of colorless, lustrous crystals, contrasting with the colored matrix rock. The size of individual crystals, although usually microscopic, also affects value – larger lamellae are rarer. The presence of associated minerals, which confirm the paragenesis, is also important. ## Popular Localities By far the best and most famous specimens come from the type locality – the Grand Reef Mine in the Aravaipa District, Arizona, USA. Specimens from this location set the standard for the species and are most desired by collectors specializing in rare or systematic minerals.
Care and storage
## Cleaning Aravaipaite specimens are extremely delicate and brittle. They should be cleaned only with great care, using compressed air to remove dust. Any contact with water or other liquids is inadvisable, as the mineral is unstable in them. ## What to Avoid Absolutely avoid contact with water and chemicals. The mineral is very soft, susceptible to scratches and mechanical damage. It should not be heated or exposed to ultrasound. Prolonged exposure to air with variable humidity can lead to its slow decomposition. ## Storage It is recommended to store specimens in sealed, dry containers (e.g., "micromount" type) under stable temperature and humidity conditions. They should be protected from dust, vibrations, and mechanical damage.