Starovaite

Chemical formula: KCu<sup>2+</sup><sub>5</sub>O(V<sup>5+</sup>O<sub>4</sub>)<sub>3</sub>

Starovaite is a very rare potassium copper vanadate, forming microscopic, tabular crystals of an intensely black color and metallic luster.

## Characteristics Starovaite is a mineral from the vanadate group, distinguished by its complex chemical composition including potassium, copper, and vanadium. It occurs as very fine, tabular or platy crystals, which rarely exceed 0.2 mm. These crystals are typically flattened and form small aggregates or appear as single flakes on the rock surface. The mineral is opaque and has a black color with a characteristic, strong metallic luster. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, or fracture, have not been precisely determined. The luster is distinctly metallic, and the streak color is black. The mineral is brittle. ## Colors and Varieties Starovaite is uniform in color – it occurs exclusively in black. No varieties have been distinguished. ## History and Name The mineral was discovered in volcanic exhalation products (fumaroles) of the Tolbachik volcano in Kamchatka, Russia. It was approved by the International Mineralogical Association (IMA) in 2018. Its name honors Galina Lvovna Starova (born 1946), a Russian crystallographer and mineralogist from St. Petersburg University, for her contributions to the study of minerals from volcanic exhalations. ## Applications Due to its extreme rarity and microscopic size, starovaite has no practical or commercial applications. It is solely an object of scientific and collector interest for specialized micromineral collectors.

Properties

Luster
Metallic
Streak
Black
Cleavage
Perfect on {0001}
Transparency
Opaque
Crystal system
Trigonal

Diagnostic features

## Identification Identification of starovaite is practically only possible using advanced analytical methods, such as Raman spectroscopy or EDS analysis, due to its microscopic size. Visually, under high magnification, characteristic black, metallic-lustered, tabular crystals can be observed. ## Distinguishing from Similar Minerals At the type locality (Tolbachik), many other black, metallic fumarolic minerals occur, e.g., piipite, shcherbinaite, or leningradite. Distinguishing it from these without specialized research equipment is impossible. ## Crystal Forms Starovaite forms very thin, tabular crystals with a hexagonal outline, flattened parallel to the {001} plane. They occur as single flakes or small, loose aggregates.

Geological environment

## Genesis Starovaite is a mineral of volcanic origin, formed by sublimation from volcanic gases in high-temperature fumaroles (exhalations). It crystallizes at temperatures of approximately 500-600°C in an oxygen-rich environment. ## Mineral Associations At the type locality, it co-occurs with many other rare fumarolic minerals, such as leningradite, piipite, lammerite, urusovite, johillerite, ericlaxmanite, popovite, and hematite. ## Localities The only confirmed occurrence of starovaite in the world is its type locality – the "Arsenatnaya" fumarole on the second slag cone of the northern breach of the Great Fissure Eruption of Tolbachik volcano in Kamchatka, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria As a micromineral, the collector value of a specimen depends on the abundance of crystals on the rock matrix, their size (though always microscopic), and their degree of development. Specimens with numerous, sharply defined crystals that can be well observed under a microscope are most prized. Association with other rare minerals from this locality is also important. ## Popular Localities The only source of specimens is the Tolbachik volcano in Kamchatka. Material from this location is extremely rare on the collector's market.

Care and storage

## Cleaning Starovaite specimens are extremely delicate and small. Mechanical or chemical cleaning is not recommended. If necessary, compressed air (from a safe distance) can be used to remove dust. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and any form of physical touch that could damage or detach the microscopic crystals from the substrate. ## Storage Specimens should only be stored in specialized "micromount" boxes that protect them from dust, shock, and humidity. Display should only be done under a microscope.

Sources

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