Wernerkrauseite
Chemical formula: CaFe³⁺₂Mn⁴⁺O₆
Wernerkrauseite is a rare calcium, iron, and manganese oxide, forming tiny, black, metallic-lustered crystals.
Properties
- Mohs hardness
- 6
- Color
- Black
- Luster
- Metallic
- Streak
- Black
- Density
- 4.66
- Cleavage
- Perfect on {0001}
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identification of wernerkrauseite is based on its characteristic appearance: black, highly lustrous, tabular microcrystals. However, identification requires specialized equipment, such as a stereoscopic microscope. Final confirmation of identity is only possible using advanced analytical methods, such as energy-dispersive spectroscopy (EDS/EDX) or X-ray diffraction (XRD). ## Distinguishing from similar minerals Wernerkrauseite can be confused with other black, metallic oxide microminerals, such as hematite, magnetite, or some spinels. Distinguishing it under amateur conditions is practically impossible. Key features include the specific crystal habit (thin tablets) and mineral associations typical of the Eifel Mountains locality. ## Crystal forms Crystals are very small, typically measuring up to 0.2 x 0.1 x 0.01 mm. They adopt the form of thin, hexagonal tablets or blades. They often form aggregates in the shape of rosettes or irregular clusters on the surface of the host rock.
Geological environment
## Genesis Wernerkrauseite forms as a result of hydrothermal or pneumatolytic processes within vesicles and fissures of basic volcanic rocks, such as leucitites and similar foid-bearing rocks. It crystallizes at high temperatures from volcanic vapors and gases (exhalations). ## Mineral associations This mineral co-occurs with other rare minerals typical of volcanic environments in the Eifel Mountains. The most common associations include: calcite, aragonite, magnetite, hematite, sharyginite, kuznetsovite, and larnite. ## Localities The only confirmed occurrence of wernerkrauseite in the world (type locality) is the Caspar quarry in the Bellerberg volcanic complex, near Ettringen and Mayen, in the Eifel region, Rhineland-Palatinate, Germany.
Rarity
Very rare
For collectors
## Quality criteria The quality of wernerkrauseite specimens is primarily assessed based on the richness and aesthetics of the microcrystal aggregates. Samples with numerous, well-formed, lustrous crystals forming dense clusters or distinct rosettes are most valued. Contrast with a light matrix (e.g., calcite) and the absence of damage to delicate crystals are also important. ## Popular localities The only source of specimens is the type locality – the Caspar quarry in Germany. All specimens available on the collector's market originate from this single location.
Care and storage
## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the microscopic size of the crystals and their fragility, any mechanical contact, including with brushes or water, should be avoided. ## What to avoid Avoid contact with chemicals, acids, and detergents. Specimens should not be subjected to ultrasonic cleaning. Protect from shocks and vibrations, which can cause delicate crystals to detach from the matrix. ## Storage Wernerkrauseite specimens should be stored in specialized "micromount" boxes, which protect them from dust and mechanical damage. Avoid exposure to moisture and extreme temperature changes.