Manganohatertite

Chemical formula: NaNaCa(Mn<sup>2+</sup>Fe<sup>3+</sup>)(As<sup>5+</sup>O<sub>4</sub>)<sub>3</sub>

Sodium, calcium, manganese, and iron arsenate of the alluaudite group, forming microscopic, brown crystals in volcanic fumaroles.

## Characteristics Manganohatertite is a rare mineral of the alluaudite group, a complex arsenate of sodium, calcium, manganese, and iron. It occurs as very small, short, prismatic crystals or granular aggregates. Its crystals rarely exceed fractions of a millimeter. The mineral is characterized by a brown to reddish-brown color and a vitreous luster. ## Physical Properties Its Mohs hardness is approximately 3.5. It is a relatively dense mineral, with a calculated density of 4.11 g/cm³. It exhibits a vitreous luster and is transparent to translucent. The streak is light brown. ## Colors and Varieties This mineral occurs in shades of brown, from common to reddish-brown. No color or commercial varieties are known. ## History and Name The name "manganohatertite" refers to the dominance of manganese in its chemical composition and its structural relationship with hatertite. It was officially recognized by the International Mineralogical Association (IMA) in 2014. Its discovery was made in volcanic exhalation products at Tolbachik volcano in Kamchatka, Russia. ## Uses Due to its extreme rarity and microscopic size of specimens, manganohatertite has no practical application. It is solely an object of scientific interest and is valued by specialized micromineral collectors.

Properties

Mohs hardness
3.5
Luster
Vitreous
Streak
Light brown
Density
4.11
Cleavage
Good on {010} and {100}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of manganohatertite is impossible without advanced analytical techniques. Due to the microscopic size of the crystals and co-occurrence with other visually similar arsenates, it requires chemical analysis (EDS/WDS) and structural analysis (X-ray diffraction, XRD). Characteristic features include its unique chemical composition and crystallographic parameters. ## Distinguishing from Similar Minerals This mineral can be confused with other brown arsenates from the same locality, such as hatertite, nickenichite, johillerite, or calciojohillerite. Visual distinction of these minerals is practically impossible and requires specialized research equipment. ## Crystal Forms Manganohatertite forms short, prismatic crystals of small size, as well as granular aggregates and coatings.

Geological environment

## Genesis Manganohatertite forms in a very specific environment – as a sublimation product in high-temperature (400-600°C) volcanic fumaroles. It crystallizes directly from volcanic gases in the oxidation zone, depositing on the surface of volcanic rocks. ## Mineral Associations It co-occurs with other rare fumarolic minerals, mainly arsenates, such as arsmirandite, calciojohillerite, johillerite, nickenichite, svabite, and tilasite. ## Localities The only confirmed occurrence of manganohatertite in the world is its type locality: the fumarole field of the second cinder cone, formed during the Great Fissure Eruption in 1975-1976 at Tolbachik volcano (Kamchatka, Far Eastern Federal District, Russia).

Rarity

Extremely rare

For collectors

## Quality Criteria For microminerals such as manganohatertite, collector value is primarily determined by the quality and development of the crystals, even if they are sub-millimeter. Specimens with sharp, well-formed crystals, preferably aesthetically grouped on a small rock matrix, are highly prized. The presence of other rare associated minerals is an additional advantage. ## Popular Localities As this mineral is known from only one location in the world, all collector specimens come from Tolbachik volcano in Kamchatka. This is a classic locality for many unique and rare fumarolic minerals.

Care and storage

## Cleaning Manganohatertite specimens are typically microminerals mounted in special boxes. Cleaning is not recommended and is usually not necessary. If needed, dust can be removed very carefully with a stream of compressed air from a safe distance. ## What to Avoid As an arsenate, the mineral is potentially toxic – avoid inhaling dust and always wash hands after contact. It should not be washed in water or exposed to any chemicals, especially acids, which can damage it. ## Storage The safest way to store it is to leave it in its original "micromount" box, which protects delicate crystals from mechanical damage, dust, and moisture.

Sources

Read more