Clino-ferri-holmquistite
Chemical formula: ◻Li₂(Mg₃Fe³⁺₂)Si₈O₂₂(OH)₂
A rare silicate from the lithium amphibole group, distinguished by its monoclinic crystallization and the presence of trivalent iron.
Properties
- Mohs hardness
- 6
- Color
- Black
- Luster
- Vitreous
- Streak
- grey
- Density
- 3.19
- Cleavage
- {110}
- Fracture
- Splintery
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Field identification of clinoferriholmquistite is practically impossible and requires advanced laboratory methods, such as X-ray diffraction (XRD) and chemical analysis (e.g., electron microprobe). Preliminary identification is based on its dark blue to black color, prismatic crystal form, and specific geological environment (lithium pegmatites). ## Differentiation from Similar Minerals This mineral is extremely difficult to distinguish from other dark amphiboles, such as arfvedsonite, riebeckite, or ferroholmquistite. Ferroholmquistite crystallizes in the orthorhombic system, while clinoferriholmquistite crystallizes in the monoclinic system, a feature that can only be verified by diffraction methods. Distinguishing it from other sodium and lithium amphiboles requires precise chemical analysis. ## Crystal Forms It most commonly forms elongated, columnar, or prismatic crystals. It also occurs as fibrous, radial, or tangled aggregates.
Geological environment
## Genesis Clinoferriholmquistite is a magmatic mineral, crystallizing in the late stages of the evolution of lithium-rich granitic pegmatites. It forms as a result of metasomatism, i.e., the reaction of lithium-rich fluids with minerals of the surrounding rocks, such as amphibolites or ultramafic rocks. ## Mineral Associations This mineral co-occurs with other minerals typical of lithium pegmatites. The most common associations include quartz, albite, microcline, as well as other lithium minerals such as spodumene, lepidolite, or tourmaline (elbaite). It may also occur in association with biotite. ## Localities This is an extremely rare mineral. It has been identified in very few localities worldwide. The type locality (the place of its first discovery and description) is in the Ozero Vostochnoye area on the Kola Peninsula in Russia. Other confirmed occurrences include pegmatites in Sweden.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a collector's specimen depends primarily on the degree of crystal development and their size. Well-formed, single prisms with an intense, dark blue color are most highly valued. Aesthetic associations with other minerals, such as contrasting white feldspars or quartz, also enhance its appeal. Due to its rarity, even microscopic but well-identified crystals have significant scientific and collectible value. ## Popular Localities Practically the only source of specimens of collector significance is the type locality on the Kola Peninsula in Russia. Specimens from other, few localities are usually material of purely scientific importance.
Care and storage
## Cleaning Specimens should be cleaned mechanically only, using a soft brush to remove dust. For heavier soiling, compressed air can be used. Avoid washing in water, especially if the specimen is fragile or consists of fibrous aggregates. ## What to Avoid It is absolutely essential to avoid contact with acids and other chemicals that could damage the mineral's structure. It should not be heated or subjected to ultrasound. Prolonged exposure to direct sunlight is not recommended, although there is no evidence of it fading. ## Storage Clinoferriholmquistite specimens, especially those with a delicate, acicular structure, should be stored in closed display boxes to protect them from dust and mechanical damage. Avoid storage in areas with high humidity.