Zemkorite
Chemical formula: Na<sub>2</sub>Ca(CO<sub>3</sub>)<sub>2</sub>
Zemkorite is a rare sodium and calcium carbonate, forming tiny, hexagonal plates and rosettes in kimberlites.
Properties
- Mohs hardness
- 3
- Luster
- Vitreous, Pearly
- Streak
- White
- Density
- 2.57
- Cleavage
- Perfect on {0001}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
Diagnostic features
## Identification Identifying zemkorite in the field or in a collection is extremely difficult without specialized equipment. Key features include its occurrence in kimberlites, the form of tiny, hexagonal plates forming rosettes, and its reaction with hydrochloric acid. However, definitive confirmation requires advanced analytical methods such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS). ## Distinguishing from Similar Minerals Zemkorite can be confused with other small, white secondary minerals in kimberlites, such as calcite, shortite, or eitelite. Calcite has different crystal forms (rhombohedra, scalenohedra) and does not form such characteristic rosettes of hexagonal plates. Shortite and eitelite, although chemically and environmentally similar, differ in crystallographic system and optical properties, which can only be determined through laboratory studies. ## Crystal Forms The mineral forms characteristic, thin, tabular or platy crystals with a hexagonal outline. These crystals almost always occur as radial or fan-shaped aggregates, resembling rosettes.
Geological environment
## Genesis Zemkorite is a hydrothermal or metasomatic mineral, forming in the late stages of kimberlite crystallization. It forms as a result of the reaction of sodium- and carbonate-rich solutions with host rock minerals under relatively low temperature and pressure conditions. ## Mineral Associations This mineral occurs in association with other minerals typical of kimberlites, such as calcite, serpentine, phlogopite, olivine, as well as rarer sodium carbonates, e.g., shortite and eitelite. ## Localities The most important and typical locality for zemkorite is the Udachnaya-East kimberlite pipe in Yakutia, Russia. This is currently the only confirmed and well-documented locality for this mineral in the world.
Rarity
Very rare
For collectors
## Quality Criteria Zemkorite is a mineral of almost exclusively scientific importance and for very specialized collectors ("micromounts"). Specimens have no aesthetic value on a macroscopic scale. Collector value lies in possessing a well-documented specimen from a confirmed locality. Most highly prized are rock fragments with clearly visible, well-formed rosettes or crystalline aggregates of zemkorite under the microscope, preferably in association with other rare minerals. ## Popular Localities The only source of collector specimens is the Udachnaya-East kimberlite pipe in Yakutia (Russia).
Care and storage
## Cleaning Due to its softness and perfect cleavage, specimens containing zemkorite should be cleaned very carefully. The safest method is to use compressed air to remove dust. If wet cleaning is necessary, use only distilled water and a very soft brush, avoiding any scrubbing. ## What to Avoid Zemkorite, like all carbonates, is sensitive to acids, which cause it to dissolve rapidly (effervesce). Contact with household chemicals, acids, and prolonged exposure to moisture should be avoided. The mineral is brittle, so it should be protected from impacts and vibrations. ## Storage Specimens containing zemkorite, usually fragments of the host rock, are best stored in stable conditions, in closed collector boxes, to protect them from dust and mechanical damage. Sudden temperature changes should be avoided.