Vozhminite

Chemical formula: Ni<sub>4</sub>AsS<sub>2</sub>

Vozhminite is a very rare, opaque nickel arsenosulfide with a metallic luster, forming small, hexagonal crystals.

## Characteristics Vozhminite is a very rare mineral from the sulfide group. It forms small, hexagonal, tabular or prismatic crystals, usually not exceeding 0.5 mm in size. It occurs as inclusions in other minerals, most often in serpentinites. It is opaque and has a metallic luster. ## Physical Properties This mineral is characterized by a hardness of approximately 4 on the Mohs scale. It has a metallic luster and is opaque. Its density, calculated based on the chemical formula and unit cell parameters, is 7.16 g/cm³. ## Colors and Varieties Vozhminite ranges in color from creamy white to light brown, often with a pinkish hue. No varieties have been distinguished. ## History and Name The mineral's name comes from its discovery locality – the Vozhmin ultramafic massif in northern Karelia, Russia. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1981. ## Uses Due to its extreme rarity and microscopic crystal sizes, vozhminite has no industrial application and is solely an object of scientific interest and a collector's item for specialized rare mineral collectors.

Properties

Mohs hardness
4
Luster
Metallic
Streak
Black
Density
7.16
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of vozhminite is possible almost exclusively using advanced laboratory methods, such as chemical composition analysis (EDS/WDS) with an electron microscope or X-ray diffraction (XRD). Under a reflected light ore microscope, it shows weak anisotropy. ## Differentiation from Similar Minerals It can be confused with other small, metallic nickel sulfides and arsenides, such as pentlandite, heazlewoodite, or maucherite. Definitive differentiation from these minerals requires specialized chemical and structural analysis. ## Crystal Forms Vozhminite forms very small, hexagonal crystals with a tabular or short-prismatic habit. It usually occurs as single, isolated crystals or small aggregate inclusions within other minerals.

Geological environment

## Genesis Vozhminite is a hydrothermal mineral associated with ultramafic rocks (peridotites) that have undergone serpentinization. It forms at relatively low temperatures as a result of metasomatic alterations of primary nickel and iron sulfides. ## Mineral Associations This mineral co-occurs with other nickel and chromium sulfides and arsenides. It is most commonly associated with heazlewoodite, orcelite, chromite, magnetite, as well as minerals from the serpentine group (antigorite, lizardite). ## Localities The main and so far only confirmed locality of vozhminite in the world is its type locality – the Vozhmin massif in the Severnaya Karelia region of Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria For a mineral as rare as vozhminite, the primary criterion for value is the confirmed presence of the mineral on the specimen itself. The most desirable samples are those in which vozhminite crystals, despite their microscopic size, are well-formed and visible under magnification. The abundance of occurrence (number of inclusions) on the rock matrix also increases the specimen's value. ## Popular Localities The only source of vozhminite specimens is its discovery locality in Russia, which makes every specimen from this location unique.

Care and storage

## Cleaning Specimens containing vozhminite, due to the microscopic nature of its occurrences, generally do not require cleaning. If necessary, use only compressed air to remove dust. Avoid contact with water and any chemicals. ## What to Avoid Avoid contact with acids and other chemical reagents that may damage both vozhminite and its associated minerals. Do not heat the specimen or subject it to ultrasound. As an arsenosulfide, it may undergo slow oxidation in a humid environment. ## Storage Specimens should be stored under stable conditions, in a dry place, away from direct sunlight and heat sources. It is best to store them in sealed collector boxes to protect them from dust and humidity changes.

Sources

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