Barioferrite

Chemical formula: BaFe₃+₁₂O₁₉

Barioferrite is a rare barium and iron oxide with strong magnetic properties, forming small, hexagonal platelets.

## Characteristics Barioferrite is an oxide from the magnetite group, chemically classified as barium hexaferrite. This mineral forms very small, thin, hexagonal (six-sided) plate-like crystals, rarely exceeding 1 mm. It usually occurs as inclusions in other minerals or as fine grains within the rock. It is opaque and has a black color with a metallic luster. ## Physical Properties Barioferrite is characterized by high hardness, approximately 7 on the Mohs scale, which is unusual for most oxides. Its density is significant, around 5.3 g/cm³. The most important physical characteristic is its strong magnetism (ferromagnetism), meaning it is permanently magnetized and strongly attracted by a magnet. ## Colors and Varieties This mineral is uniform in color and occurs exclusively in black. No color varieties or commercial forms are distinguished. ## History and Name The name "barioferrite" directly refers to its chemical composition – the presence of barium and iron (Ferrum). The mineral was first described in 1995 by B. W. Evans and J. A. Konnert based on material from a mine in Kajlidongri, India, although its synthetic counterpart had been known and industrially produced since the 1950s. ## Applications Natural barioferrite is a rarity and is of scientific and collector's interest only. Its synthetic counterpart, known as barium hexaferrite, is, however, an extremely important industrial material. Due to its strong magnetism, high resistance to corrosion and demagnetization, it is widely used in the production of permanent magnets (so-called ferrite magnets), used in electric motors, loudspeakers, toys, and as a magnetic recording medium in tapes and floppy disks.

Properties

Mohs hardness: 7
Luster: Metallic
Streak: Black
Density: 5.28
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification The key diagnostic feature of barioferrite is its very strong magnetism (it is ferromagnetic). It can be easily identified by checking its reaction to a magnet. Other features include its black color, metallic luster, high hardness, and the characteristic form of small, hexagonal platelets visible under magnification. ## Distinguishing from Similar Minerals Barioferrite can be confused with magnetite, hematite, or ilmenite. - **Magnetite** is also strongly magnetic but crystallizes in the isometric system, forming octahedra or rhombic dodecahedra, not hexagonal platelets. It also has lower hardness (5.5-6.5). - **Hematite** can form platy crystals (specular hematite), but it is only weakly magnetic (reacts to a strong neodymium magnet) and is characterized by a reddish-brown streak (barioferrite has a black streak). - **Ilmenite** is non-magnetic or very weakly magnetic and has lower hardness (5-6). ## Crystal Forms Barioferrite forms thin, tabular crystals with a hexagonal outline. They occur as single, disseminated platelets or small aggregates in the host rock.

Geological environment

## Genesis Barioferrite is a metamorphic mineral. It forms under conditions of high-pressure and relatively low-temperature metamorphism, in rocks rich in manganese and barium, such as the Kajlidongri deposits in India. It forms in the eclogite or glaucophane facies. ## Mineral Associations This mineral co-occurs with minerals such as hollandite, braunite, hematite, bixbyite-(Mn), piemontite, quartz, and minerals from the phlogopite group. ## Localities The most important and best-documented locality, which is also the type locality, is the Kajlidongri manganese mine in the Jhabua district (Madhya Pradesh, India). This is the only place from which well-formed, natural barioferrite crystals originate. It has also been identified in ultramafic rocks in Spain.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a barioferrite specimen primarily depends on the presence of well-formed crystals, visible to the naked eye or under slight magnification. The most valued specimens are those where black, lustrous, hexagonal barioferrite platelets create an aesthetic contrast with the lighter host rock. Crystal size is crucial, as most are microscopic – specimens with crystals exceeding 1 mm are exceptionally rare and sought after. ## Popular Localities The only source of collector's specimens is the Kajlidongri mine in India. Practically all natural barioferrites available on the market come from this single locality.

Care and storage

## Cleaning Barioferrite specimens are usually very small and embedded in the host rock. Cleaning should be limited to gently removing dust with a soft brush or compressed air. Due to its hardness and chemical stability, it can be washed in distilled water and then thoroughly dried. ## What to Avoid Avoid contact with strong acids, which could damage the host rock. Despite its high hardness, the crystals are brittle and can be mechanically damaged if handled carelessly. It does not require special protection from light or temperature. ## Storage Store in stable conditions, in a closed display box, to protect small crystals from dust and mechanical damage. Due to its strong magnetism, specimens should be kept away from sensitive electronic devices and magnetic data storage media (credit cards, hard drives).

Sources

IMA Mineral List (CNMNC)