Perovskite

Chemical formula: CaTi⁴⁺O₃

Perovskite is a calcium titanium oxide, forming characteristic, pseudocubic crystals with a metallic or submetallic luster.

## Characteristics Perovskite is a calcium titanium oxide that gave its name to an entire, structurally important group of minerals. It forms crystals with an appearance similar to cubic (cubes, octahedra), although it actually crystallizes in the orthorhombic system. Crystal surfaces are often covered with striations. It is usually opaque, less often translucent, and its luster is described as metallic to submetallic or adamantine. ## Physical Properties Its Mohs hardness is 5.5, placing it in the same category as apatite. It is relatively dense, with a specific gravity of approximately 3.98 g/cm³. It exhibits indistinct cleavage. ## Colors and Varieties The most common colors of perovskite are black, dark brown, and reddish-brown. It also occurs in yellow hues. Some varieties rich in niobium (knopite) or cerium and lanthanum (dysanalite) may show slight differences in appearance and properties. ## History and Name The mineral was first described in 1839 by Gustav Rose. The name was given in honor of the Russian mineralogist, Count Lev Alekseevich Perovsky (1792-1856). ## Applications Perovskite and materials with its crystal structure (so-called perovskite materials) are of immense importance in science and technology, especially in the production of photovoltaic cells, catalysts, and electronics. Natural specimens primarily have scientific and collecting significance.

Properties

Mohs hardness: 5.5
Luster: Metallic, Adamantine
Streak: Colourless, greyish white
Density: 3.98
Cleavage: On {001}.
Fracture: Irregular/Uneven,Sub-Conchoidal
Transparency: Transparent,Translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Perovskite is most easily recognized by its characteristic, pseudocubic (often cubic) crystals, dark color (black to brown), and metallic or adamantine luster. A Mohs hardness of 5.5 and a white or grayish-white streak are also important diagnostic features. ## Distinguishing from Similar Minerals Perovskite is sometimes confused with magnetite, but magnetite is strongly magnetic, while perovskite is not. It differs from garnets (e.g., schorlomite) by its lower hardness and different crystal form. Galena, although having a similar luster and form, is much denser, softer, and has perfect cleavage. ## Crystal Forms Perovskite crystals most often take the form of cubes, octahedra, or combinations thereof. They frequently exhibit striations on their faces. It also occurs in granular aggregates and crusts.

Geological environment

## Genesis Perovskite forms in various geological environments. It occurs as an accessory mineral in basic and ultrabasic igneous rocks, such as kimberlites, carbonatites, and nepheline syenites. It is also found in contact skarns formed by the metamorphism of impure limestones, and in some chlorite and talc schists. ## Mineral Associations This mineral often co-occurs with magnetite, ilmenite, nepheline, leucite, apatite, chlorite, titanite, and minerals from the garnet and pyroxene groups. ## Localities The most important historical locality, from which the first described specimens originated, is the Akhmatov mine in the Ural Mountains, Russia. Other known localities include the Kola Peninsula (Russia), the Zermatt area (Switzerland), the Malenco Valley (Italy), Magnet Cove in Arkansas (USA), and numerous occurrences in carbonatites and kimberlites in Canada, Brazil, and Africa.

Rarity

Not very common

For collectors

## Quality Criteria The most valued specimens by collectors are those with sharp, well-formed, and undamaged crystals with a strong luster. The size of the crystals is of great importance – those exceeding a centimeter are highly prized. Aesthetic placement of crystals on a contrasting rock matrix adds to their attractiveness. ## Popular Localities Classic, historical specimens come from the Urals in Russia. Currently, sharp, black crystals from the Kola Peninsula (Russia), as well as specimens from Switzerland and Italy, are highly valued. Specimens from Magnet Cove in Arkansas (USA) also belong to the classics of the species.

Care and storage

## Cleaning Perovskite specimens should be cleaned carefully, using a soft brush and distilled water. Short baths in ultrasonic cleaners can be used, but with great caution to avoid damaging the fragile crystal edges. ## What to Avoid Avoid contact with strong acids, which can damage the mineral's surface. Perovskite is stable under normal conditions, but extreme temperature changes and strong mechanical impacts should be avoided due to its brittleness. ## Storage Collector's specimens of perovskite are best stored in separate boxes or on stands to prevent scratching by harder minerals. It does not require special protection from light or humidity.