Iwateite

Chemical formula: Na₂BaMn₂+(PO₄)₂

Iwateite is a very rare sodium, barium, and manganese phosphate, forming colorless, tabular crystals with a vitreous luster.

## Characteristics Iwateite is a mineral from the phosphate group, chemically classified as a sodium, barium, and manganese phosphate. It occurs as very small, tabular or bladed crystals, reaching sizes up to 0.3 mm. The crystals are typically colorless and transparent, which, combined with their small size, makes them difficult to observe with the naked eye. ## Physical Properties This mineral is characterized by a vitreous luster. Its Mohs hardness is 5, placing it in the same category as apatite. The density of iwateite is relatively high, at 4.35 g/cm³. ## History and Name Iwateite was discovered in the Tanohata mine in Iwate Prefecture, Japan, from which its name is derived. It was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2013 (IMA2013-088). It was described by a Japanese team of mineralogists, including Ritsuro Miyawaki and Koichi Momma.

Properties

Mohs hardness: 5
Luster: Vitreous
Streak: White
Density: 4.35
Cleavage: Perfect on {0001}
Fracture: Uneven
Transparency: Transparent
Crystal system: Hexagonal

Diagnostic features

## Identification Identification of iwateite is possible only through advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). Visual recognition in the field or even in a collection is practically impossible due to the microscopic size of the crystals and the lack of characteristic macroscopic features. ## Distinguishing from Similar Minerals Based on appearance, it is indistinguishable from many other colorless microscopic minerals found in similar parageneses, such as quartz, barite, or other rare phosphates. Certain differentiation requires specialized laboratory equipment. ## Crystal Forms Iwateite crystallizes as very small, thin, tabular crystals, often with a hexagonal outline, which reflects its internal hexagonal symmetry. Crystals occur as single flakes or small aggregates on the surface of other minerals.

Geological environment

## Genesis Iwateite forms in manganese deposits embedded in siliceous rocks (cherts) that have undergone contact metamorphism. It occurs in hydrothermal veins cutting through these deposits. Its formation is associated with the interaction of hot solutions with rocks rich in manganese, barium, and phosphorus. ## Mineral Associations This mineral coexists with other manganese and barium minerals. In the type locality (Tanohata mine), it was found in association with rhodochrosite, barite, quartz, tephroite, alabandite, as well as very rare minerals such as tanohataite and watanabeite. ## Localities The only confirmed location of iwateite in the world is its type locality - the Tanohata mine, located in Iwate Prefecture on Honshu Island, Japan.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, iwateite is not evaluated according to typical criteria such as size or color. The collector's value of a specimen primarily depends on the confirmed presence of the mineral through analysis and on the richness and aesthetics of the associated minerals on the rock matrix. The most valuable samples are those where iwateite is well-formed and occurs in association with other rare species from this locality.

Care and storage

## Cleaning Due to the extreme rarity and small size of the crystals, mechanical cleaning of iwateite specimens is not recommended and should only be performed by specialists under laboratory conditions. If it is necessary to remove loose dust, compressed air can be used from a safe distance. ## What to Avoid Avoid contact with all chemicals, especially acids, which can damage the mineral. The crystals are brittle, so they should be protected from impacts, vibrations, and sudden temperature changes. ## Storage Iwateite specimens, due to their scientific value and rarity, should be stored under stable conditions in specialized micromount boxes, protecting them from dust, humidity, and mechanical damage. They should not be exposed to direct sunlight.

Sources

IMA Mineral List (CNMNC)