Iseite

Chemical formula: Mn<sup>2+</sup><sub>2</sub>Mo<sup>4+</sup><sub>3</sub>O<sub>8</sub>

Iseite is an extremely rare molybdenum and manganese oxide, forming microscopic, black crystals with a metallic luster.

## Characteristics Iseite is a mineral from the oxide group, described in 2011. It occurs as very fine, tabular or bladed crystals, reaching up to 0.2 mm in size. It typically forms radial aggregates or appears as single, scattered crystals within the host rock. It is opaque and black in color. ## Physical Properties Iseite crystals exhibit a strong, metallic luster. The mineral's hardness on the Mohs scale is approximately 5.5. It is a brittle mineral with a black streak. The density calculated based on its chemical formula and unit cell parameters is 6.23 g/cm³. ## History and Name The mineral's name comes from its discovery locality – the Ise mine in Fukui Prefecture, Japan. It was approved by the International Mineralogical Association (IMA) in 2011 under number 2011-034. The type material (holotype) is preserved in the collections of the National Museum of Nature and Science in Tsukuba, Japan.

Properties

Mohs hardness
5.5
Luster
Metallic
Streak
Black
Density
6.23
Cleavage
Perfect on {001}
Fracture
Uneven
Transparency
Opaque
Crystal system
Monoclinic

Diagnostic features

## Identification Iseite identification is only possible using advanced analytical methods, such as Raman spectroscopy, X-ray diffraction (XRD), and chemical analysis using an electron microprobe (EDS/WDS). Visually, it is indistinguishable from many other black, metallic minerals. ## Distinguishing from similar minerals It can be confused with other manganese and molybdenum oxides, such as kamiokite, with which it co-occurs. Definitive differentiation requires specialized chemical and structural analysis. ## Crystal forms It forms very small, tabular or bladed crystals, often grouped into radial aggregates.

Geological environment

## Genesis Iseite forms as a result of hydrothermal processes in molybdenum deposits. At its discovery locality (Ise mine), it occurs in quartz veins cutting altered volcanic rocks (rhyodacites) from the Cretaceous period. ## Mineral associations This mineral co-occurs with quartz, kamiokite, molybdenite, titanite, muscovite, and minerals from the chlorite group. ## Localities The only confirmed locality of iseite in the world is its type locality – the Ise mine, near Ōno city, in Fukui Prefecture, Japan.

Rarity

Extremely rare

For collectors

## Quality criteria As a microscopic mineral, iseite is primarily valued by collectors specializing in "micromounts" and rare minerals (so-called "rare species collectors"). The value of a specimen is determined by the abundance of well-formed crystals on the rock matrix and confirmation of identification through analysis. ## Popular localities The only source of specimens is the Ise mine in Japan, which makes them extremely difficult to acquire on the collector's market.

Care and storage

## Cleaning Due to the extreme rarity and small size of the crystals, mechanical cleaning is not recommended and should only be performed by specialists. Specimens should be protected from dust. ## What to avoid Avoid contact with chemicals, acids, and bases. The mineral is brittle, so it should be protected from impacts and vibrations. Ultrasonic cleaning should not be used. ## Storage Iseite specimens, due to their microscopic nature, should be stored in specialized "micromount" boxes, protecting them from mechanical damage and dust. Avoid exposure to moisture and extreme temperatures.

Sources

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