Epifanovite

Chemical formula: NaCaCu₂+₅(PO₄)₄[As₅+O₂(OH)₂]·₇H₂O

Epifanovite is a very rare, blue mineral from the phosphate and arsenate group, discovered in products of volcanic activity in Kamchatka.

## Characteristics Epifanovite is a hydrated phosphate and arsenate of sodium, calcium, and copper. It forms aggregates of thin, tabular crystals, not exceeding 0.2 x 0.1 x 0.01 mm in size, which often arrange into rosette-like or fan-shaped aggregates. It is a secondary mineral, formed by the interaction of volcanic gases with basalt. ## Physical Properties Epifanovite crystals exhibit a vitreous luster. The mineral is brittle. Due to the small size of the crystals, precise determination of hardness and density was not possible; however, the density calculated based on the formula and unit cell parameters is 3.23 g/cm³. ## Colors and Varieties This mineral is characterized by an intense blue color. No color varieties or commercial varieties have been observed. ## History and Name The mineral's name honors the Russian geologist and writer Pavel Pavlovich Epifanov (1942–2001). It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2016 (IMA2016-053). It was described by a team of mineralogists led by Igor V. Pekov based on specimens found in fumarolic products of Tolbachik volcano in Kamchatka, Russia.

Properties

Luster: Vitreous
Streak: Light blue
Density: 3.23
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Triclinic

Diagnostic features

## Identification Identification of epifanovite is based on its unique occurrence environment (volcanic fumaroles), characteristic blue color, and form of thin, tabular crystals forming rosette aggregates. Final identification requires advanced analytical methods such as X-ray diffraction (XRD) and chemical analysis (EDS). ## Distinguishing from Similar Minerals Epifanovite can be confused with other blue secondary copper minerals found in the same environment, such as cyanotrichite, chalcanthite, or other rare arsenates and phosphates. Distinguishing it "in the field" is practically impossible and requires specialized laboratory equipment. ## Crystal Forms Crystals are very thin, tabular, with outlines resembling rectangular or lath-like shapes. They usually occur as fan-shaped or rosette-like clusters and aggregates.

Geological environment

## Genesis Epifanovite is a mineral of volcanic origin, crystallizing in the zone of hot gases (fumaroles). It forms as a product of sublimation or as a result of reactions of volcanic gases rich in arsenic, phosphorus, and fluorine with basaltic rocks at temperatures of approximately 100-150°C. ## Mineral Associations This mineral coexists with other rare fumarolic minerals such as alexite, atlasovite, avdoninite, eriochalcite, florenskyite, jarosite, lammerite, nabokoite, piipite, tenorite, and hematite. ## Localities The only confirmed locality of epifanovite in the world is its type locality – the "Arsenatnaya" fumarole field at the second cone of the northern eruption of Tolbachik volcano in Kamchatka, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the collector's value of epifanovite depends on the richness of crystal aggregates on the rock matrix, the intensity of the blue color, and the aesthetics of the clusters themselves. Specimens with clearly formed, undamaged crystal rosettes that contrast well with the substrate are most valued. ## Popular Localities The only source of epifanovite specimens is its discovery site at Tolbachik volcano in Kamchatka. Material from this locality is extremely rare and sought after by specialized collectors of systematic and "micromount" minerals.

Care and storage

## Cleaning Due to its extreme rarity, small crystal size, and fragility, epifanovite specimens should not be cleaned mechanically or chemically. Any impurities should be left undisturbed. ## What to Avoid Contact with water, chemicals, ultrasound, and sudden temperature changes should be avoided. As a hydrated mineral, it can dehydrate in a dry environment or under heat, leading to its destruction. It should be protected from direct sunlight. ## Storage Epifanovite specimens require storage under stable conditions, preferably in closed, padded "micromount" containers that protect against mechanical damage, dust, and humidity fluctuations.

Sources

IMA Mineral List (CNMNC)