Taramite

Chemical formula: Na(NaCa)(Mg₃Al₂)(Si₆Al₂)O₂₂(OH)₂

Taramite is a rare, black or dark green amphibole group mineral, found mainly in metamorphic rocks.

## Characteristics Taramite is a complex silicate of sodium, calcium, magnesium, and aluminum, belonging to the amphibole group. It typically forms granular or fibrous aggregates, and less commonly, poorly developed, prismatic crystals. Its appearance is usually inconspicuous, and specimens range in color from black to very dark, blue-green. ## Physical Properties This mineral has a hardness of 5-6 on the Mohs scale. It has a vitreous luster and is translucent. The density calculated from crystallographic data is approximately 3.23 g/cm³. ## Colors and Varieties The predominant color of taramite is black, often with blue or green hues. Specimens with a uniform, deep blue-green color are also found. No named varieties of this mineral are distinguished. ## History and Name The mineral's name comes from Tarama, a district in Ehime Prefecture, Japan, where a similar mineral was first identified (later disqualified, but the name was transferred to the newly defined species). It was described as a distinct mineral species in 1997. The type locality, from which reference specimens originate, is the Liset eclogite deposit in Norway. ## Uses Taramite has no industrial applications. It is a mineral of purely scientific and collector's interest, sought after by specialists and advanced collectors of rare minerals.

Properties

Mohs hardness: 5-6
Luster: Vitreous
Streak: White
Density: 3.231
Cleavage: {110} good
Fracture: Uneven
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identifying taramite in the field is difficult due to its resemblance to other black amphiboles. Key features include its black or dark green color, vitreous luster, and occurrence in specific metamorphic rocks, such as eclogites. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical microanalysis (EDS/WDS). ## Distinguishing from Similar Minerals Taramite is almost impossible to distinguish with the naked eye from other black amphiboles, such as hornblende, arfvedsonite, or glaucophane. Hornblende occurs in a wider range of rocks, and arfvedsonite often exhibits weak pleochroism. Final differentiation is only possible based on chemical and structural analysis. ## Crystal Forms Taramite crystallizes in the monoclinic system. It most commonly forms granular, fibrous, or columnar aggregates. Well-formed, single prismatic crystals are very rare and small.

Geological environment

## Genesis Taramite is a characteristic mineral of metamorphic rocks that have undergone transformation under conditions of high pressure and moderate to high temperatures. It forms mainly in eclogites, amphibolites, and gneisses. ## Mineral Associations This mineral often co-occurs with other minerals typical of metamorphic rocks, such as omphacite, garnet (especially pyrope and almandine), quartz, kyanite, phengite, paragonite, and rutile. ## Localities The most important and type locality for taramite is the Liset eclogite deposit in the Vestland region of Norway. It is also known from several other locations worldwide where suitable metamorphic rocks occur, including Syros in Greece, the Alps in Austria and Italy, and the Novosibirsk region in Russia.

Rarity

Very rare

For collectors

## Quality Criteria For collectors, specimens with well-formed, even if small, crystals are most desirable, which is a great rarity. Specimens with an intense, blue-green color are also valued. The presence of taramite in association with other rare metamorphic minerals, such as omphacite or kyanite, forming aesthetic associations, enhances its attractiveness. ## Popular Localities By far the most valued and well-known taramite specimens come from the type locality – Liset in Norway. Material from this location is considered exemplary for this mineral species.

Care and storage

## Cleaning Taramite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. After wet cleaning, the specimen should be thoroughly dried. ## What to Avoid Avoid contact with strong acids and bases, which can damage the mineral's surface. Taramite is sensitive to sudden temperature changes. It should not be exposed to prolonged direct sunlight, which can cause it to fade. ## Storage Taramite specimens are best stored in separate, padded boxes or display cases to prevent scratching by harder minerals. Fibrous aggregates can be brittle, so they should be protected from impacts and vibrations.

External references

https://www.mindat.org/min-6798.html