Kolovratite

Chemical formula: (Ni²⁺,Zn²⁺)xV⁵⁺O₄·nH₂O

Kolowratite is a rare hydrated nickel and zinc vanadate, forming soft, earthy coatings and aggregates of a yellowish-green color.

## Characteristics Kolowratite is a rare mineral from the vanadate group, chemically classified as a hydrated nickel and zinc vanadate. It most commonly occurs as earthy, powdery, or compact masses, as well as thin crusts and coatings on host rocks. Due to its structure, it rarely forms any crystalline shapes and is usually found in amorphous or microcrystalline form. Its typical appearance is soft, dull aggregates. ## Physical Properties Kolowratite is a very soft mineral, with a Mohs hardness of only 1-2, meaning it can be scratched with a fingernail. It has a dull or earthy luster and is opaque. Its density is variable, depending on the exact chemical composition and degree of hydration, but it is estimated to be around 3.1 g/cm³. ## Colors and Varieties This mineral is characterized by a typical color palette ranging from pistachio green, through yellowish-green, to yellow. The color is directly related to the presence of nickel and vanadium ions in its structure. No named varieties of this mineral are distinguished. ## History and Name The mineral was named in honor of Evgeny Lvovich Kolovrat-Chervinsky (1881-1915), a Russian chemist who died on the front during World War I. The mineral was first described in 1922 by Vladimir Vernadsky based on samples from Ferghana, Uzbekistan.

Properties

Mohs hardness: 2-3
Color: Citrine-yellow, greenish yellow
Luster: Dull
Streak: Pale yellow.
Density: 0
Cleavage: None
Fracture: Irregular/Uneven,Conchoidal
Transparency: Translucent
Crystal system: Amorphous

Diagnostic features

## Identification Kolowratite can be identified by its characteristic yellowish-green or pistachio color, very low hardness (1-2 on the Mohs scale), and earthy or powdery mode of occurrence. It usually forms thin coatings and crusts on other minerals or rocks. ## Distinguishing from Similar Minerals It can be confused with other secondary nickel or vanadium minerals, such as annabergite (usually more intensely green) or tyuyamunite (usually more yellow and radioactive). Final distinction often requires chemical analysis to confirm the simultaneous presence of nickel, zinc, and vanadium. ## Crystal Forms Kolowratite is an amorphous mineral or occurs as microcrystalline aggregates. It does not form crystals visible to the naked eye. Its typical forms are earthy masses, powdery coatings, crusts, and compact aggregates.

Geological environment

## Genesis Kolowratite is a secondary mineral, forming in the oxidation zones of deposits containing vanadium, nickel, and zinc minerals. It forms as a result of the weathering of primary ores under near-surface conditions. Its formation is associated with the presence of metal-rich bituminous shales. ## Mineral Associations It often co-occurs with other vanadate minerals, such as tyuyamunite, carnotite, as well as with gypsum, calcite, and clay minerals. It can also accompany other secondary nickel and zinc minerals. ## Localities The most important and historical locality, from which the type material originates, is the Ferghana Valley in Uzbekistan. It is also known from several localities in the United States, especially in San Miguel County, Colorado, and in the Paradox Valley area. Occurrences have also been reported in Germany (Thuringia) and Argentina.

Rarity

Rare

For collectors

## Quality Criteria The quality of a kolowratite specimen primarily depends on the intensity and purity of its color and the abundance of its occurrence on the host rock. Specimens where the mineral forms thick, uniform, and well-colored coatings or crusts are most valued. The contrast with the rock matrix also enhances the visual appeal of the specimen. ## Popular Localities Specimens from the classic locality in the Ferghana Valley, Uzbekistan, are of historical significance. Currently, samples from the American states of Colorado and Utah also appear on the collector's market, valued for their good quality and intense color.

Care and storage

## Cleaning Kolowratite specimens are extremely delicate, soft, and often porous. Wet cleaning should be avoided, as water can damage or dissolve the fragile aggregates. If cleaning is absolutely necessary, a very soft brush can be used to gently remove dust. ## What to Avoid Contact with water, acids, chemical agents, and ultrasonic cleaners must be strictly avoided. The mineral is very soft, so it should be protected from scratches, impacts, and abrasion. It should not be heated or exposed to prolonged moisture. ## Storage Kolowratite should be stored in a dry, stable environment, preferably in a closed collector's box, to protect it from dust and mechanical damage. Due to its fragility, it is not suitable for display in open showcases where it could be exposed to touch or vibrations.

External references

https://www.mindat.org/min-2242.html