Rusinovite

Chemical formula: Ca₁₀(Si₂O₇)₃Cl₂

Rusinovite is a very rare mineral from the sorosilicate group, forming colorless to white, granular aggregates, discovered within xenoliths in the Hatrurim Formation in Israel.

## Characteristics Rusinovite is a mineral belonging to the sorosilicates, with a very complex crystal structure. It occurs as very fine, anhedral (lacking crystal faces) grains, which form dense, compact aggregates. Individual grains rarely exceed 50 micrometers in size. It is a colorless to white mineral with a vitreous luster. ## Physical Properties Due to the extremely small size of the grains, most physical properties have not been precisely determined. Hardness is estimated at approximately 5.5 on the Mohs scale. The density calculated based on the formula and unit cell parameters is 2.83 g/cm³. The mineral does not exhibit fluorescence under ultraviolet light. ## Colors and Varieties The mineral is colorless to white. No varieties have been distinguished. ## History and Name Rusinovite was approved as a new mineral by the International Mineralogical Association (IMA) in 2010 (IMA2010-037). Its name honors Vladimir Lvovich Rusinov (1935–2007), a Russian mineralogist and petrologist, specialist in metasomatic and hydrothermal processes, who made significant contributions to the study of the Hatrurim Formation, where this mineral was discovered. It was described by a team of mineralogists: Evgeny V. Galuskin, Irina O. Galuskina, J. Kusz, P. Duda, B. Ternes, and M. Murashko. ## Applications Rusinovite has no practical applications. It is solely an object of scientific and collecting interest due to its extreme rarity and unique formation environment.

Properties

Mohs hardness: 5.5
Luster: Vitreous
Streak: White
Density: 2.83
Cleavage: None
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of rusinovite is impossible without advanced analytical techniques. This requires chemical analysis (e.g., using an electron microprobe - EDS/WDS) and structural studies (X-ray diffraction - XRD). Visually, it appears as fine, colorless or white grains in the host rock. ## Distinguishing from similar minerals Based on appearance, it is indistinguishable from many other white, granular minerals found in the Hatrurim Formation, such as larnite, brownmillerite, mayenite, or jasmundite. Definitive differentiation is only possible through chemical and crystallographic analysis. ## Crystal forms Rusinovite forms exclusively anhedral, irregular grains up to 50 micrometers in size, which intergrow into dense, massive aggregates.

Geological environment

## Genesis Rusinovite forms under pyrometamorphic conditions, i.e., contact metamorphism at very high temperatures, exceeding 800°C. It forms within xenoliths of carbonate rocks (limestones and marls) entrained and altered by volcanic effusions or as a result of natural combustion of bitumens. It is a product of reactions between silicates and chlorides in a calcium-rich environment. ## Mineral associations This mineral co-occurs with other high-temperature minerals typical of the Hatrurim Formation (the so-called "Hatrurim marbles"). It is most commonly associated with: larnite, brownmillerite, jasmundite, mayenite, ye'elimite, fluorapatite, fluorellestadite, wurtzite, and perovskite. ## Localities The only confirmed locality of rusinovite in the world is its type locality: the Hatrurim Formation in the Negev Desert, Israel. This is a unique geological complex, known for the occurrence of many rare minerals formed by pyrometamorphic processes.

Rarity

Extremely rare

For collectors

## Quality criteria The quality of a rusinovite specimen depends solely on the abundance and confirmed presence of this mineral in the host rock. As it is a microscopic mineral, specimens are evaluated based on scientific analysis rather than aesthetic value. The most valuable samples are those in which rusinovite forms larger (though still microscopic) aggregates and co-occurs with other rare minerals from this locality. ## Popular localities The only source of specimens is the Hatrurim Formation in Israel. Specimens are extremely difficult to acquire and appear on the collector's market sporadically, most often from scientific institutions or researchers specializing in this locality.

Care and storage

## Cleaning Rusinovite specimens are typically microscopic and occur within the host rock. They do not require and should not be subjected to mechanical or chemical cleaning, which could damage delicate grains and associated minerals. ## What to avoid Avoid contact with acids and all chemicals. Due to the presence of chlorine in its composition, it may theoretically be sensitive to moisture and temperature changes, although its stability has not been thoroughly investigated. Specimens should be protected from mechanical damage. ## Storage Specimens containing rusinovite should be stored under stable conditions, in a dry place, away from direct sunlight and dust. The best solution is to store them in a specialized "micromount" box or a perky box, with an accurate label.

Sources

IMA Mineral List (CNMNC)