Ferro-papikeite
Chemical formula: NaFe²⁺₅Al₂(Si₅Al₃)O₂₂(OH)₂
Ferro-papikeite is a rare, pale beige amphibole group mineral, discovered in the Nordmark mining district in Sweden.
Properties
- Mohs hardness
- 6
- Luster
- Vitreous
- Streak
- colorless to very pale brown
- Density
- 3.488
- Cleavage
- {210}; cleavage systems intersecting at ~56°
- Fracture
- Splintery
- Transparency
- Translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identifying ferro-papikeite in field conditions is practically impossible without advanced analytical methods. In a collection, it is identified based on its pale beige color, fibrous or prismatic appearance, and specific cleavage. However, a key aspect is its association with the type locality (Nordmark, Sweden) and confirmation of its chemical composition (high iron and sodium content). ## Distinguishing from Similar Minerals Ferro-papikeite can be confused with other amphiboles of similar appearance, such as other minerals from the papikeite group, tremolite, or actinolite. Definitive differentiation requires chemical analysis (EDS/WDS) or X-ray diffraction (XRD) to determine the exact composition and crystal structure. ## Crystal Forms This mineral forms elongated, prismatic crystals, often occurring as fibrous aggregates or radial clusters.
Geological environment
## Genesis Ferro-papikeite forms in metamorphic rocks, particularly in skarns and iron and manganese ore deposits that have undergone contact metamorphism. Its formation is associated with specific pressure and temperature conditions and the appropriate chemical composition of the surrounding rocks. ## Mineral Associations At its type locality in Sweden, ferro-papikeite coexists with minerals such as andradite, magnetite, hedenbergite, quartz, and other amphiboles. ## Localities The only confirmed and thoroughly described occurrence of ferro-papikeite in the world is its type locality: the historic Nordmark mining district in Filipstad municipality, Värmland region, Sweden.
Rarity
Very rare
For collectors
## Quality Criteria As a mineral of primarily scientific importance, the most valuable specimens are those rich in well-formed crystals that can be subjected to analysis. Association with other minerals from the type locality is also crucial. The purity and intensity of color are of secondary importance, as this mineral does not stand out for its aesthetic qualities. ## Popular Localities The only source of collectible specimens is the type locality in the Nordmark district of Sweden. Material from this location is extremely difficult to acquire and appears on the market very rarely, mainly in specialized circulation.
Care and storage
## Cleaning Ferro-papikeite specimens should only be cleaned mechanically, using a soft, dry brush or compressed air to remove dust. Due to its rarity and potential chemical sensitivity, contact with water and all cleaning agents should be avoided. ## What to Avoid Avoid contact with acids and other chemicals that may react with the mineral's components. It should also be protected from high temperatures and sudden temperature changes. Although not particularly light-sensitive, prolonged exposure to strong sunlight is not recommended. ## Storage It is recommended to store specimens in stable conditions, in closed boxes or display cases, to protect them from dust, moisture, and mechanical damage. Due to its splintery fracture, it should be handled with care.