Charmarite
Chemical formula: Mn<sup>2+</sup><sub>4</sub>Al<sub>2</sub>(OH)<sub>12</sub>CO<sub>3</sub>·3H<sub>2</sub>O
Charmarite is a very rare, hydrated manganese and aluminum hydroxycarbonate, forming delicate, hexagonal, white crystals with a pearly luster.
Properties
- Mohs hardness
- 2
- Luster
- Pearly
- Streak
- White
- Density
- 2.58
- Cleavage
- Perfect on {0001}
- Fracture
- Uneven
- Transparency
- Transparent to Translucent
- Crystal system
- Trigonal
Diagnostic features
## Identification Charmarite is identified by its characteristic form – small, hexagonal, tabular crystals, often grouped into rosette-like aggregates. Key features also include its white color, pearly luster, low hardness, and flexibility (but not elasticity). It reacts with acids, which is a diagnostic feature, but this test is destructive and not recommended for such a rare mineral. ## Distinguishing from Similar Minerals Charmarite can be confused with other minerals from the hydrotalcite group, such as manasseite or quintinite. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS). Visually, it may resemble some micas or other tabular minerals, but it differs from them in crystal habit and occurrence environment. ## Crystal Forms The mineral forms thin, tabular crystals with a hexagonal outline. These crystals often combine into rosettes, spherical aggregates, or form coatings and efflorescences on other minerals.
Geological environment
## Genesis Charmarite is a secondary mineral, forming in the late stages of hydrothermal processes in complex, alkaline nepheline syenite intrusions. It forms in rock cavities and fractures as a result of alterations of other, earlier minerals. ## Mineral Associations At the type locality (Mont Saint-Hilaire), charmarite is associated with minerals such as quartz, microcline, aegirine, natrolite, analcime, rhodochrosite, petersenite-(Ce), and other rare alkaline minerals. ## Localities The most important and best-known locality for charmarite in the world is the Poudrette quarry in Mont Saint-Hilaire, Quebec, Canada, which is its type locality. This is the only confirmed site from which well-formed specimens of this mineral originate.
Rarity
Very rare
For collectors
## Quality Criteria The most prized charmarite specimens are those with well-formed, sharp, and undamaged crystals forming aesthetic rosettes or groups. Crystal size is also important – the larger, the more valuable, although even the largest rarely exceed 1 mm. Contrast with the matrix and the presence of rare associated minerals can significantly increase the value of a specimen. ## Popular Localities The only source of collectible charmarite specimens is the Mont Saint-Hilaire quarry in Quebec, Canada. Specimens from this locality are the standard for this mineral.
Care and storage
## Cleaning Charmarite specimens should be handled with the utmost care. Mechanical cleaning is highly inadvisable due to the extreme delicacy of the crystals. If absolutely necessary, compressed air can be used from a safe distance to remove loose dust. Contact with water, which can damage the mineral, should be avoided. ## What to Avoid Contact with water, acids, and other chemicals must be strictly avoided. The mineral is sensitive to changes in temperature and humidity. It should not be exposed to direct sunlight, which can cause dehydration and destruction. Vibrations and shocks can easily damage delicate aggregates. ## Storage Charmarite specimens are best stored in original, padded "micromount" boxes or in sealed containers that protect them from dust, humidity, and mechanical damage. Display should be in stable conditions, away from heat and light sources.