Flinkite
Chemical formula: Mn²⁺₂Mn³⁺As⁵⁺O₄(OH)₄
Flinkite is a rare manganese arsenate, forming small, prismatic crystals with a characteristic greenish-brown color.
Properties
- Mohs hardness
- 4.5
- Luster
- Vitreous to resinous
- Streak
- Yellowish-brown
- Density
- 3.87
- Cleavage
- Good on {100}, poor on {010}
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Flinkite can be identified by its characteristic greenish-brown color, vitreous luster, and typical fan-shaped or radial aggregates of small, prismatic crystals. Its occurrence in paragenesis with other rare manganese arsenates in specific localities is a key diagnostic clue. ## Distinguishing from Similar Minerals It can be confused with other greenish or brownish manganese arsenates, such as allactite or hematolite, with which it often co-occurs. Definitive differentiation usually requires advanced analytical methods, such as X-ray diffraction (XRD), due to visual similarity and co-occurrence in the same deposits. ## Crystal Forms Flinkite crystals are typically small and prismatic, elongated along one axis. They often arrange themselves into radial, fan-shaped, or nearly spherical aggregates, growing on a rock substrate or in fissures.
Geological environment
## Genesis Flinkite is a secondary mineral, formed as a result of metamorphic processes in iron and manganese ore deposits. It forms in fissures and rock vugs in skarns or metamorphosed, layered Fe-Mn deposits. ## Mineral Associations This mineral co-occurs with many other, often rare, manganese minerals. Its typical associations include: hausmannite, baryte, allactite, hematolite, brandtite, sarkinite, manganberzeliite, tephroite, and pyrochroite. It also occurs with calcite and other carbonates. ## Localities The most important and classic locality for flinkite is its type locality – the Harstigen mine in Pajsberg, Persberg district (Sweden). This is the main source of the best specimens of this mineral. Outside of Sweden, its presence has also been noted in the Sterling Hill mine in Ogdensburg (New Jersey, USA), which is known for the occurrence of many rare manganese minerals.
Rarity
Very rare
For collectors
## Quality Criteria The most prized flinkite specimens are those with well-formed, sharp crystals forming aesthetic, fan-shaped or radial aggregates. An intense, greenish-brown color and good luster are important. A contrasting placement on a light matrix, for example on calcite, significantly enhances visual appeal and specimen value. Due to the small size of the crystals, the size of the aggregates is also an important factor. ## Popular Localities By far the most sought-after and classic specimens come from the Harstigen mine in Sweden. Material from this locality is considered the benchmark for the species. Specimens from the Sterling Hill mine in the USA are also valued by collectors specializing in minerals from this deposit, although they are much rarer on the market than those from Sweden.
Care and storage
## Cleaning Flinkite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its potential reactivity, contact with water, and especially with chemicals, should be avoided. If a liquid is necessary, distilled water or isopropyl alcohol is recommended at most, used in minimal amounts and with quick drying. ## What to Avoid Avoid all acids and strong detergents, which can damage or chemically alter the mineral. Flinkite is relatively soft, so it must be protected from scratching by harder minerals. It should not be heated or exposed to prolonged intense light. ## Storage It is recommended to store flinkite in a separate, padded display box to prevent abrasions and mechanical damage. It is best kept in stable room conditions, away from moisture and direct sunlight, which could affect its color over time.