Proto-ferro-suenoite

Chemical formula: ◻Mn²⁺₂Fe²⁺₅Si₈O₂₂(OH)₂

Proto-ferro-suenoite is a rare amphibole group silicate, forming fibrous or prismatic crystals ranging in color from white to brownish-yellow.

## Characteristics Proto-ferro-suenoite is a silicate mineral, specifically belonging to the amphibole group (suenoite subgroup). It occurs as small, prismatic or fibrous crystals, often forming radial aggregates or tangled masses. Its color is usually inconspicuous, ranging from white, through grayish, to brownish-yellow. Due to its rarity and small crystal size, it is primarily of interest to specialized collectors and scientists. ## Physical Properties This mineral has a hardness of 5.5-6 on the Mohs scale, placing it on par with many other silicates. It exhibits a vitreous luster. It is a relatively light mineral. Its crystals are typically translucent. ## Colors and Varieties Observed colors of proto-ferro-suenoite include shades of white, gray, and brownish-yellow. No distinct color varieties or commercial forms have been identified. ## History and Name The mineral's name refers to its chemical composition (dominance of iron - *ferro*) and its structural relationship with suenoite, while the prefix *proto-* indicates its orthorhombic crystallographic symmetry. It was first described in 1984 based on material from the Nippyo mine in Tochigi Prefecture, Japan, which is its type locality.

Properties

Mohs hardness
5.5-6
Luster
Vitreous
Streak
White to greyish-white
Density
0
Cleavage
(210)
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Amateur identification of proto-ferro-suenoite is practically impossible and requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (e.g., electron microprobe). Preliminary identification is based on crystal habit (fibrous, prismatic), co-occurrence with other manganese and iron minerals, and knowledge of the locality. ## Distinguishing from Similar Minerals This mineral is visually indistinguishable from other amphiboles of similar habit, especially from the cummingtonite-grunerite series and other members of the suenoite group. Definitive differentiation is possible only through detailed laboratory studies. ## Crystal Forms Proto-ferro-suenoite forms elongated, prismatic crystals with an orthorhombic cross-section. It often occurs as fibrous, tangled, or radial aggregates.

Geological environment

## Genesis This is a mineral formed as a result of metamorphic processes in iron- and manganese-rich rocks. In its type locality (Nippyo mine), it occurs in metamorphosed manganese deposits. ## Mineral Associations It co-occurs with other manganese and iron minerals, such as rhodochrosite, dannemorite, tephroite, galaxite, pyroxmangite, and spessartine. ## Localities The most important and best-documented occurrence is its type locality – the Nippyo (Yokoneyama) mine in Tochigi Prefecture, Japan. This is the only confirmed locality for this mineral.

Rarity

Very rare

For collectors

## Quality Criteria Due to its extreme rarity, every documented and correctly identified specimen of proto-ferro-suenoite is valuable to specialized collectors of rare minerals (so-called "micromounts"). The most desirable specimens are those with well-formed crystals visible under a microscope, rich in the mineral, and originating from the type locality. ## Popular Localities The only source of collector specimens is the Nippyo mine in Japan. Material from this location is extremely difficult to acquire on the market.

Care and storage

## Cleaning Specimens should be cleaned very carefully, preferably using compressed air to remove dust. If necessary, a soft brush can be used. Due to the fibrous nature of the aggregates, avoid washing in water, which could remain between the fibers. ## What to Avoid Avoid contact with strong acids and chemicals, which can damage the mineral. Brittle, fibrous aggregates are sensitive to impacts and vibrations. Do not subject it to ultrasound or sudden temperature changes. ## Storage It is recommended to store specimens in closed, padded collector boxes to protect them from dust, mechanical damage, and moisture. This is especially important for delicate, fibrous aggregates.

External references

Sources

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