Efremovite
Chemical formula: (N<sup>3-</sup>H<sub>4</sub>)<sub>2</sub>Mg<sub>2</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>3</sub>
Efremovite is a very rare ammonium-magnesium sulfate, forming small, colorless crystals in fumarolic environments on burning coal dumps.
Properties
- Luster
- Vitreous
- Density
- 2.29
- Transparency
- Transparent
- Crystal system
- Isometric
Diagnostic features
## Identification The diagnostic feature of efremovite is primarily its unique occurrence environment – fumarolic products on burning coal dumps. Identification is facilitated by the regular form of small, colorless crystals and a vitreous luster. A key test, though destructive, is its easy solubility in water. ## Distinguishing from Similar Minerals Efremovite can be confused with other sulfates formed under similar conditions, such as mascagnite (ammonium sulfate) or boussingaultite (ammonium-magnesium sulfate). Distinguishing them based on visual characteristics is very difficult and most often requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis. ## Crystal Forms Efremovite crystals crystallize in the isometric system and most often take the form of small, well-formed octahedra, less often cubes or their combinations. It is also found as granular aggregates and as fine coatings on host rocks.
Geological environment
## Genesis Efremovite is a mineral of anthropogenic origin, formed as a result of fumarolic processes on burning mine dumps. It forms as a product of sublimation from hot gases at temperatures from 50 to 200°C, reacting with clay rocks and shales. It is a typical secondary mineral, crystallizing under specific thermal and chemical conditions. ## Mineral Associations This mineral co-occurs with other sulfates and chlorides formed in the same environment. The most common associated minerals include godovikovite, mascagnite, boussingaultite, native sulfur, and sal ammoniac. ## Localities The most important and best-documented efremovite localities in the world are its type locality – the burning dump in Kopeisk in the Chelyabinsk Coal Basin, Russia. It is also known from burning dumps in Ravat, Tajikistan, and from uranium mining dumps in the Ronneburg area in Thuringia (Germany).
Rarity
Very rare
For collectors
## Quality Criteria In the case of such a rare mineral as efremovite, the main criterion of value is its mere presence in a collection. Specimens with well-formed, sharp-edged crystals are most prized, even if they are microscopic in size. Transparency and lack of damage are also important. Specimens on matrix, in association with other rare fumarolic minerals, are particularly desirable. ## Popular Localities The vast majority of collector specimens come from two classic localities for minerals of this type: the burning dumps in Chelyabinsk (Russia) and Ravat (Tajikistan). Specimens from these locations are considered reference for this species.
Care and storage
## Cleaning Efremovite is water-soluble, so its cleaning must be done exclusively dry. A very soft brush or compressed air from a safe distance can be used to remove dust and loose contaminants. ## What to Avoid Contact of the mineral with water, water vapor, and any other liquids that could damage or completely dissolve it must be strictly avoided. The mineral is hygroscopic and sensitive to moisture in the air, so it should not be exposed in humid rooms. ## Storage Efremovite specimens require storage in dry conditions. The best solution is to place them in a tightly sealed container, such as a "micromount" box or a display case with a desiccant (silica gel). This protects the mineral from changes in atmospheric humidity.