Ognitite

Chemical formula: NiBiTe

Ognitite is a very rare nickel tellurobismuthide, occurring as fine, metallic grains in association with other ore minerals.

## Characteristics Ognitite is an extremely rare mineral from the sulfide group, specifically a nickel tellurobismuthide. It occurs as very small, anhedral (irregular) grains, typically not exceeding 100 micrometers in size. It is primarily observed in polished ore sections under a microscope, where it forms inclusions within other minerals. It has a metallic luster and a creamy-white color with a pinkish hue. ## Physical Properties Due to the extremely small size of its grains, most of ognitite's physical properties have not been precisely determined. The mineral exhibits a strong, metallic luster. Its hardness and density have not been measured, only theoretically calculated. It is opaque. ## Colors and Varieties Ognitite has a consistent, characteristic creamy-white color with a distinct pinkish or pinkish-brown hue. It does not form color varieties or commercial variants. ## History and Name The mineral was first identified in material from the Ognit deposit in Eastern Siberia, Russia. It was described and approved by the International Mineralogical Association (IMA) in 1982. The name "ognitite" comes directly from the name of its discovery locality (type locality). ## Uses Ognitite has no industrial or commercial applications. Its significance is purely scientific, and it is of interest to collectors specializing in very rare systematic minerals.

Properties

Luster
Metallic
Transparency
Opaque
Crystal system
Trigonal

Diagnostic features

## Identification Identification of ognitite is possible only through advanced laboratory techniques. Under a reflected light ore microscope, it is characterized by a creamy-white color with a pinkish hue and a strong metallic luster. Final confirmation requires chemical analysis using an electron microprobe (EDS/WDS) to confirm the presence of nickel, bismuth, and tellurium in appropriate proportions. ## Differentiation from Similar Minerals Under the microscope, it can be confused with other tellurides of similar hue, such as melonite or some phases in the bismuth-tellurium system. Differentiation relies solely on precise chemical composition analysis. ## Crystal Forms Ognitite does not form visible crystals. It occurs exclusively as fine, irregular grains and inclusions within other minerals.

Geological environment

## Genesis Ognitite is a hydrothermal mineral. It forms in the final stages of crystallization from solutions rich in nickel, bismuth, and tellurium, under low to medium temperature conditions. Its presence has been noted in quartz-calcite veins cutting ultramafic rocks (serpentinites). ## Mineral Associations This mineral occurs in paragenesis with other rare ore minerals. It is most commonly associated with maucherite, nickeline, heazlewoodite, pentlandite, native copper, native bismuth, melonite, altaite, and platinum-group minerals (PGM). ## Localities The only confirmed and well-documented occurrence of ognitite in the world is its type locality – the Ognit nickel-copper deposit in the Eastern Sayan Mountains, Siberia, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of an ognitite specimen is assessed quite differently than for minerals forming large crystals. The most important criterion is the confirmation of the mineral's presence through chemical analysis. The value of a specimen is enhanced by the richness of the mineral association visible in the section, as well as the size (even if only tens of micrometers) and "purity" of the analyzed ognitite grain. These specimens are valuable exclusively to specialized systematic mineral collectors and scientific institutions. ## Popular Localities The only source of specimens is the Ognit deposit in Russia.

Care and storage

## Cleaning Specimens containing ognitite (usually polished sections or blocks) should only be cleaned with compressed air to remove dust. Any contact with liquids or chemicals is inadvisable. ## What to Avoid Avoid ultrasonic cleaners, all chemical agents, acids, and bases. Protect the surface of the polished section from scratching and oxidation. Do not expose the specimen to temperature changes. ## Storage Ognitite specimens should be stored in a dry place, in a specialized collector's box (a "micromount box"), to protect them from dust, moisture, and mechanical damage. It is best to keep them under stable room conditions.

Sources

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