Dmisteinbergite

Chemical formula: CaAl₂Si₂O₈

Dmisteinbergite is a hexagonal polymorph of anorthite, a rare tectosilicate mineral found mainly in contact metamorphic zones and in some meteorites.

## Characteristics Dmisteinbergite is a very rare mineral belonging to the tectosilicate group, with the same chemical composition as common anorthite (CaAl₂Si₂O₈), but with a different, hexagonal crystal structure. For this reason, it is classified as a polymorph of anorthite. It typically occurs as very small, thin, hexagonal plates or flakes, often forming radial aggregates or rosettes. Individual crystals rarely exceed 1 mm in size. Due to its small size, its visual characteristics are difficult to observe without magnification. ## Physical Properties Dmisteinbergite crystals exhibit a vitreous to pearly luster, especially on cleavage surfaces. The mineral is transparent to translucent. Its Mohs hardness is approximately 6, and its density is slightly lower than anorthite, around 2.67 g/cm³. It possesses perfect cleavage in one direction. ## Colors and Varieties Dmisteinbergite is usually colorless or white. No colored or commercial varieties have been distinguished. ## History and Name The mineral was first described in 1990 based on findings from two localities: the active Tolbachik volcano in Kamchatka (Russia) and the Hatrurim copper deposit in Israel. Its name honors Dmitry Sergeyevich Steinberg (1910-1992), a Russian geologist and petrologist from the Institute of Geology and Geochemistry in Yekaterinburg, for his contributions to the study of ultramafic rocks and chromitites in the Urals. ## Uses Dmisteinbergite has no industrial application. Its significance is purely scientific and collectible, as a rare polymorph of anorthite with an unusual structure.

Properties

Mohs hardness: 6
Luster: Vitreous to pearly
Streak: White
Density: 2.67
Cleavage: Perfect on {0001}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Hexagonal

Diagnostic features

## Identification Identifying dmisteinbergite is extremely difficult without advanced analytical methods. Preliminary identification in a collection relies on the hexagonal outline of very small, thin, platy crystals, often in radial aggregates. The mineral exhibits a characteristic, bright blue fluorescence under ultraviolet light (both shortwave and longwave). However, final confirmation requires methods such as X-ray diffraction (XRD) or Raman spectroscopy to distinguish it from other minerals with similar appearance and composition. ## Distinguishing from Similar Minerals Dmisteinbergite is most often confused with its triclinic polymorph, anorthite, and other feldspars. Distinguishing it from anorthite "by eye" is practically impossible and requires analysis of its crystal structure. It can also be confused with other white or colorless minerals forming small flakes, such as gypsum or some micas, but it differs from them in hardness and crystal form. ## Crystal Forms Dmisteinbergite crystals occur as thin, hexagonal tablets and flakes. They often form fan-shaped or radial aggregates, as well as small, rosette-like clusters on the surface of the host rock.

Geological environment

## Genesis Dmisteinbergite is a high-temperature mineral, forming under specific conditions. It forms in contact metamorphic zones, where carbonate rocks (limestones, marls) are subjected to very high temperatures, as in the Hatrurim Formation in Israel. It also forms as a sublimation product in volcanic exhalations, as observed at the Tolbachik volcano. It has also been identified as a component of some carbonaceous chondrites (Allende meteorite), where it occurs in calcium- and aluminum-rich inclusions (CAIs). ## Mineral Associations The mineral is often accompanied by other high-temperature minerals of contact metamorphism and volcanic products. Depending on the locality, it co-occurs with minerals such as: anorthite, gehlenite, larnite, wollastonite, diopside, grossular, spinel, and in fumarole products, also hematite. ## Localities The most important and classic localities for dmisteinbergite are the Hatrurim metamorphic complex in the Negev Desert, Israel, and the eruption products of the Tolbachik volcano in Kamchatka, Russia. This mineral has also been confirmed in the Allende meteorite, which fell in Mexico. Besides these locations, its occurrence has been noted in only a few other places worldwide, including the Eifel Mountains in Germany.

Rarity

Very rare

For collectors

## Quality Criteria Dmisteinbergite is typically a "micromount" mineral, meaning its collectible value does not depend on the size of the specimen, but on the quality of the microscopic crystals. Most prized are specimens with well-formed, sharp, hexagonal crystals forming aesthetic, radial or rosette-like aggregates. The purity of the crystals (transparency) and lack of damage are also important. Contrast with the color of the host rock can enhance the visual appeal of the specimen. ## Popular Localities The most classic and sought-after specimens by collectors come from the two type localities: the Hatrurim Formation in Israel and the Tolbachik volcano in Kamchatka. Specimens from these locations are considered reference examples for this mineral species.

Care and storage

## Cleaning Dmisteinbergite specimens are usually very small and delicate, embedded in a rock matrix. Cleaning should be kept to an absolute minimum. If necessary, compressed air can be used to remove loose dust. Avoid contact with water and any chemical agents. ## What to Avoid Avoid ultrasonic cleaning, steam cleaning, and contact with acids and other chemicals. Due to its perfect cleavage, the mineral is sensitive to impacts and mechanical pressure. It should be protected from sudden temperature changes. ## Storage Specimens should be stored in stable conditions, in a sealed "micromount" box, to protect them from dust, mechanical damage, and moisture. It is not sensitive to light, but protection from dust is crucial for preserving the aesthetics of the tiny crystals.

Sources

IMA Mineral List (CNMNC)