Kayrobertsonite
Chemical formula: Mn<sup>2+</sup>Al<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>(OH)<sub>2</sub>·6H<sub>2</sub>O
Kayrobertsonite is a very rare hydrated manganese and aluminum phosphate, forming microscopic, colorless or pale pink crystals.
Properties
- Mohs hardness
- 3
- Luster
- Vitreous
- Streak
- White
- Density
- 2.45
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Triclinic
Diagnostic features
## Identification Identification of kayrobertsonite is practically only possible using advanced analytical methods, such as X-ray diffraction (XRD) and chemical spectroscopy (EDS/WDS). Visually, it is indistinguishable from many other rare phosphates of the laueite group. Characteristic features include microscopic, bladed crystals in radial aggregates, occurring in a specific pegmatitic environment. ## Differentiation from Similar Minerals Kayrobertsonite can be confused with other minerals from the laueite group, such as laueite, stewartite, or pseudolaueite. They differ in chemical composition (e.g., the presence of iron instead of manganese) and subtle differences in crystallographic parameters, which require laboratory confirmation. ## Crystal Forms It forms flattened, bladed or tabular crystals elongated along the crystallographic axis. These crystals often combine into small, radial or rosette aggregates.
Geological environment
## Genesis Kayrobertsonite is a secondary mineral, formed in complex granite pegmatites rich in phosphates. It forms as a result of hydrothermal alteration of primary manganese phosphates, such as triplite, in oxidation zones. ## Mineral Associations This mineral co-occurs with other rare phosphates. In the type locality (Foote mine), it was found in association with strengite, rockbridgeite, laueite, stewartite, jahnsite-(CaMnMn), and wardite. ## Localities Its occurrence has been confirmed in only two locations worldwide. The type locality is the Foote Lithium Co. mine in Cleveland County, North Carolina, USA. The second known locality is the Córrego do Urucum quarry in Minas Gerais, Brazil.
Rarity
Very rare
For collectors
## Quality Criteria As a microscopic mineral, kayrobertsonite is primarily valued by collectors specializing in "micromounts" and rare and systematic minerals. Specimens with well-formed, sharp crystals forming aesthetic, radial aggregates are most highly rated. A rich association with other rare phosphates on the same rock matrix is also important. Color, due to its paleness, is of secondary importance. ## Popular Localities Both known localities – the Foote mine in the USA and the Córrego do Urucum quarry in Brazil – provide specimens of collecting significance, with material from the type locality being historically the most important.
Care and storage
## Cleaning Kayrobertsonite specimens are extremely delicate and small, therefore mechanical or chemical cleaning is not recommended. Any attempts at cleaning may destroy the fragile crystals. It is best to leave them in their untouched state. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and sudden temperature changes. The mineral is sensitive to dehydration, which can lead to its damage. It should be protected from dust and vibrations. ## Storage It is recommended to store specimens exclusively in sealed, lockable "micromount" boxes, which protect them from physical damage, dust, and humidity changes. Display should only occur under magnification, without direct contact with the specimen.