Dashkovaite

Chemical formula: Mg(HCOO)¹⁻₂·₂H₂O

Dashkovaite is a rare organic mineral, hydrated magnesium formate, forming colorless, acicular crystals in the oxidation zones of coal deposits.

## Characteristics Dashkovaite is a mineral from the group of organic substances, specifically hydrated magnesium formate. It occurs as fine, acicular or hair-like crystals, which often form radial aggregates, rosettes, or spherulites. Individual crystals are usually very small, reaching up to 1 mm in length and only a few micrometers in thickness. The mineral is colorless and transparent, with a vitreous luster. ## Physical Properties Dashkovaite is a very soft mineral, with a Mohs hardness of approximately 1. It has a low density, close to 1.58 g/cm³. It exhibits perfect cleavage in one direction. It is elastic and flexible, which is an unusual characteristic for minerals. ## History and Name The mineral was named after Yekaterina Romanovna Vorontsova-Dashkova (1743-1810), director of the Russian Academy of Sciences and president of the Russian Academy. It was discovered in an underground fire zone in a brown coal mine near the city of Kopeysk, in the Southern Urals, Russia. It was described in 1963. ## Uses Dashkovaite has no industrial application. Due to its rarity, unusual origin, and delicate structure, it is a prized collector's mineral, sought after by specialized collectors.

Properties

Mohs hardness: 1
Color: White
Luster: Vitreous
Streak: White
Density: 0
Cleavage: Perfect on {010}
Fracture: Irregular/Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Dashkovaite can be identified by its characteristic form – it creates small, colorless, acicular or hair-like crystals gathered in radial aggregates. Its extreme softness, low density, and elasticity are key diagnostic features. It reacts with acids and dissolves in water. ## Distinguishing from similar minerals It can be confused with other organic minerals or secondary sulfates of similar appearance, such as epsomite or gypsum. It is distinguished from them by its perfect cleavage, elasticity, and solubility in water. Final identification requires advanced analytical methods, such as infrared (IR) spectroscopy or X-ray diffraction (XRD). ## Crystal forms Crystals are strongly elongated, acicular or hair-like (acicular habit). They usually occur as radial or stellate aggregates and spherulites. Single, isolated crystals are rarely observed.

Geological environment

## Genesis Dashkovaite is a secondary mineral, forming under very specific conditions. It forms as a result of the reaction of formic acid-rich solutions with magnesium-containing minerals, such as dolomite. Formic acid is a product of the slow oxidation or distillation of brown coal in the zones of underground fires in mine dumps. ## Mineral associations This mineral co-occurs with other rare organic minerals, such as formicaite, as well as with calcite, dolomite, and native sulfur. ## Localities The most important and typical occurrence of dashkovaite is brown coal mine No. 45 in Kopeysk, Chelyabinsk Oblast, Southern Urals, Russia. This is the only confirmed and well-documented locality for this mineral in the world.

Rarity

Very rare

For collectors

## Quality criteria The most prized specimens by collectors are those with well-formed, rich aggregates of acicular crystals, forming aesthetic rosettes or "urchins" on the host rock (matrix). The size of the aggregates and the absence of damage are important, which is difficult to achieve due to the mineral's fragility. Contrast with a dark coal rock background enhances visual appeal. ## Popular localities The only source of collector specimens is the historical type locality – the mine in Kopeysk, Russia. Material from this location is very rarely available on the market.

Care and storage

## Cleaning Dashkovaite specimens are extremely delicate and sensitive to water. They should not be cleaned wet. Only very careful dust removal with a soft brush or a stream of compressed air from a distance is permissible. ## What to avoid Contact with water, which can dissolve the mineral, must be absolutely avoided. It should be protected from all chemicals, high temperatures, and humidity. Specimens are very fragile and susceptible to mechanical damage. ## Storage It is recommended to store specimens in airtight, sealed "micromount" boxes, which protect against moisture, dust, and physical damage. Avoid exposure to direct sunlight and humidity changes.

External references

https://www.mindat.org/min-10175.html