Chlormagaluminite
Chemical formula: Mg₄Al₂(OH)₁₂Cl₂(H₂O)₂
Chlormagaluminite is a rare magnesium and aluminum hydroxychloride, forming small, hexagonal crystals with a pearly luster.
Properties
- Mohs hardness
- 1.5-2.5
- Luster
- Pearly, Vitreous
- Streak
- White
- Density
- 1.98
- Cleavage
- {0001}
- Transparency
- Translucent
- Crystal system
- Hexagonal
Diagnostic features
## Identification Chlormagaluminite is difficult to identify visually due to the small size of its crystals. Key features include the hexagonal outline of crystals, pearly luster on cleavage surfaces, very low hardness, and occurrence in specific geological environments (kimberlites, basic rocks). ## Distinguishing from Similar Minerals It can be confused with other minerals from the hydrotalcite or quintinite group, such as quintinite or charmarite. Differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS), to confirm the dominance of chlorine and the absence of a carbonate group. ## Crystal Forms It forms thin, tabular crystals with a hexagonal (six-sided) outline. They often occur as small, rosette-like or spherulitic clusters and aggregates.
Geological environment
## Genesis It is a secondary mineral, formed as a result of low-temperature hydrothermal processes or serpentinization. It forms in veins cutting kimberlites, as well as in ultramafic igneous rocks, such as dunites. ## Mineral Associations It most commonly co-occurs with serpentine, iowaite, magnetite, perovskite, diopside, phlogopite, and minerals from the hydrotalcite group. ## Localities The most important and type locality is the Kapaevskaya kimberlite pipe on the Angara River in Siberia, Russia. It has also been reported in the ophiolite complex in Okayama Prefecture, Japan, and in the Palabora mine in the Republic of South Africa.
Rarity
Very rare
For collectors
## Quality Criteria The collector's appeal of a specimen primarily depends on the presence of well-formed, even microscopic, crystals with a distinct hexagonal outline. Specimens where crystals are grouped into aesthetic rosettes or clearly stand out from the host rock (matrix) are highly valued. Due to its rarity, any well-documented specimen holds value for specialized collectors. ## Popular Localities The only source of specimens of collector's significance is its type locality – the Kapaevskaya pipe in Russia.
Care and storage
## Cleaning Specimens should be cleaned very carefully, using only a soft brush to remove dust. Due to its low hardness and potential reactivity, contact with water and any chemical agents should be avoided. ## What to Avoid Contact with water, acids, and other chemicals must be strictly avoided. The mineral is very soft and brittle, susceptible to scratches and mechanical damage. It should be protected from high temperatures, which can cause the loss of water from its structure. ## Storage It is recommended to store specimens in stable conditions, in closed, padded collector's boxes, to protect them from mechanical damage, dust, and humidity changes.