Zincorinmanite-(Zn)

Chemical formula: Zn₂+Sb₅+(Fe₃+₂Zn₂+)O₇(OH)

Zincorinmanite-(Zn) is an extremely rare mineral from the rinmanite group, an oxide of zinc, antimony, and iron, discovered in Sweden.

## Characteristics Zincorinmanite-(Zn) is an exceptionally rare mineral that visually manifests as black, opaque grains with a metallic luster. It typically occurs as anhedral (irregularly shaped) grains not exceeding 0.5 mm in size, often intergrown with other minerals. Its identification is possible only through advanced analytical methods, such as electron spectroscopy and X-ray diffraction. ## Physical Properties This mineral is characterized by high hardness, estimated at 6.5 on the Mohs scale. It has a black streak and a metallic luster. It is brittle, and its fracture is uneven. The density calculated based on the chemical formula and unit cell parameters is 5.71 g/cm³. ## History and Name Zincorinmanite-(Zn) was officially recognized by the International Mineralogical Association (IMA) in 2021 under number IMA2021-042. Its name refers to its chemical composition – the dominance of zinc (Zn) – and its relation to the rinmanite mineral structure. It was discovered in material originating from the historic Moss mine, located in Filipstad Municipality, Värmland region, Sweden.

Properties

Mohs hardness: 6.5
Luster: Metallic
Streak: Black
Density: 5.71
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification Identification in field or home conditions is impossible. Zincorinmanite-(Zn) can only be identified based on chemical analysis (EDS/WDS) confirming the presence of zinc, antimony, and iron in appropriate proportions, and structural analysis (X-ray diffraction) confirming its hexagonal crystal structure. Visually, it is simply a black, metallic grain. ## Distinguishing from similar minerals It can be confused with many other black, metallic oxide minerals, such as magnetite, ilmenite, franklinite, or other minerals from the hematite and spinel groups. Differentiation requires specialized analytical equipment. ## Crystal forms To date, it has only been observed in the form of anhedral (irregular) grains, often forming intergrowths with other minerals.

Geological environment

## Genesis Zincorinmanite-(Zn) forms as a result of metamorphic processes in rocks rich in zinc and iron. In its type locality (Moss mine), it occurs in skarns, which are metamorphic rocks formed at the contact of a magmatic intrusion with carbonate sedimentary rocks (e.g., dolomites). ## Mineral associations This mineral co-occurs with minerals such as: magnetite, gahnospinel (a zinc-rich variety of spinel), hedenbergite, hornblende, phlogopite, and minerals from the serpentine group. ## Localities The only confirmed occurrence (type locality) is the historic Moss mine, Nordmark Odal Field, Filipstad Municipality, Värmland, Sweden.

Rarity

Extremely rare

For collectors

## Quality criteria Zincorinmanite-(Zn) is a mineral of purely scientific and systematic significance. It does not form visually attractive specimens for the typical collector. Its value lies in its extreme rarity and being part of a well-documented find from the type locality. Microscopic grains on matrix, whose identity has been analytically confirmed, would be most highly valued.

Care and storage

## Cleaning Due to its extreme rarity and small grain size, specimens of zincorinmanite-(Zn) are not subject to standard cleaning. Any manipulation should be kept to an absolute minimum and performed only under laboratory conditions using specialized equipment, e.g., tweezers under a microscope. ## What to avoid Avoid contact with any chemicals, ultrasound, and sudden temperature changes. The mineral is brittle, so it should be protected from impacts and abrasions. ## Storage Microscopic specimens of this type are stored in specialized, sealed "micromount" boxes, protecting them from dust, moisture, and mechanical damage. Storage under stable room conditions is sufficient.

Sources

IMA Mineral List (CNMNC)