Frolovite

Chemical formula: Ca[B(OH)₄]₂

Frolovite is a rare hydrated calcium borate, forming colorless, granular aggregates and tabular crystals with a vitreous luster.

## Characteristics Frolovite is a hydrated calcium borate, usually occurring as colorless or white, granular and massive aggregates. Less frequently, it forms small, tabular or bladed crystals, which can reach up to 2 mm in length. It is a transparent to translucent mineral, with a vitreous luster, and a slightly greasy luster on fracture surfaces. ## Physical Properties This mineral is characterized by relatively low hardness, measuring 3.5 on the Mohs scale, which makes it susceptible to scratching. Its density is low, ranging from 2.15-2.27 g/cm³. It does not exhibit fluorescence under ultraviolet light. ## Colors and Varieties Frolovite is typically colorless or white. No colored varieties or trade names have been described. ## History and Name The mineral's name comes from the Russian geologist Nina Vasilyevna Frolova (1909-1973), who conducted research on boron deposits in the Urals. Frolovite was first described in 1957 by E. I. Petrova, based on material found in magnesium skarns in the area of the Novo-Frolovskoye copper deposit in the Urals, Russia. ## Uses Due to its rarity and small crystal size, frolovite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or borate minerals.

Properties

Mohs hardness
3.5
Color
White, with a grayish tint
Luster
Vitreous
Streak
White
Density
2.14
Cleavage
Perfect on {100}, good on {010} and {001}
Fracture
Uneven
Transparency
Opaque
Crystal system
Triclinic

Diagnostic features

## Identification Frolovite is difficult to identify visually without advanced examination. Its key features include its occurrence as colorless, granular aggregates in skarns, low hardness (around 3.5), and vitreous luster. Definitive identification requires chemical analysis (EDS) or X-ray diffraction (XRD) to confirm its composition (calcium borate) and crystal structure. ## Distinguishing from Similar Minerals It can be confused with other colorless borates, such as colemanite, hydroboracite, or howlite, as well as calcite or quartz. It is distinguished from calcite by its lack of reaction with hydrochloric acid. It is much softer than quartz. Distinguishing it from other borates is very difficult and usually requires specialized analytical methods. ## Crystal Forms Frolovite crystals are rare and have a tabular or bladed habit. Most often, it forms massive, fine-grained, or compact aggregates.

Geological environment

## Genesis Frolovite is a secondary mineral, forming in the oxidation zones of boron deposits. It forms in magnesium and calcareous skarns that have undergone hydrothermal processes. It results from the alteration of pre-existing borates, such as szaibelyite, under low-temperature conditions. ## Mineral Associations This mineral co-occurs with other borates, such as szaibelyite, wimsite, olshanskyite, pentahydroborite, as well as with calcite, dolomite, garnets (andradite, grossular), and magnetite. ## Localities The most important and classic locality for frolovite is the area of the Novo-Frolovskoye copper deposit near Krasnoturinsk in the Northern Urals, Russia. It is also known from several other locations worldwide, including the Titovskoye boron deposit in the Tas-Khaykhtakh Mountains in Yakutia (Russia) and the Fuka mine in Okayama Prefecture, Japan.

Rarity

Very rare

For collectors

## Quality Criteria The most valued by collectors are specimens with well-formed, even if small, transparent frolovite crystals. Rich granular aggregates, clearly visible on the rock matrix, especially in association with other rare borates, are also highly prized. The purity (lack of inclusions) and transparency of the crystals increase the specimen's value. ## Popular Localities Undoubtedly, the most sought-after specimens come from the type locality in the Urals, Russia, which provided the best-studied materials. Specimens from the Fuka mine in Japan are also valued in collecting circles.

Care and storage

## Cleaning Frolovite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its low hardness, contact with harder tools can lead to scratches. The use of water is not recommended, as it may be sensitive to it as a borate. ## What to Avoid Avoid contact with water, acids, and other chemicals. The mineral is soft and brittle, so it must be protected from impacts, falls, and contact with harder minerals. It should not be heated or exposed to sudden temperature changes. ## Storage It is recommended to store frolovite specimens in separate, padded collector's boxes to prevent abrasions and mechanical damage. Keep it in a dry place, away from sources of moisture.

External references

Sources

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