Surinamite

Chemical formula: Mg₃Al₃O[Si₃BeAlO₁₅]

Surinamite is an extremely rare, greenish-blue silicate mineral, found mainly in aluminum-rich metamorphic rocks.

## Characteristics Surinamite is a very rare mineral belonging to the silicate group. It forms tabular or bladed crystals, often intergrown into small aggregates. Its most characteristic feature is an intense, greenish-blue or bluish-green color. Crystals are usually small, rarely exceeding a few millimeters in length, and often occur as inclusions in other minerals, such as quartz or cordierite. ## Physical Properties This mineral is characterized by significant hardness, measuring 7 on the Mohs scale. It has a vitreous luster and is typically translucent to transparent. The density of surinamite ranges from 3.53-3.6 g/cm³. It also exhibits weak pleochroism in shades of blue and colorless. ## Colors and Varieties Surinamite occurs in characteristic shades from greenish-blue to bluish-green. No distinct color varieties or commercial varieties have been identified. ## History and Name The mineral's name comes from Suriname, the country where it was first discovered in 1978. It was described by J.J.M.M.M. de Roever, E.A.J. Burke, P. Maaskant, and C. Kieft. Its discovery took place in granulite gneisses in the Bakhuis Mountains. ## Uses Due to its extreme rarity and small crystal size, surinamite has no industrial applications. It is solely an object of scientific and collector interest for specialized collectors.

Properties

Mohs hardness: 7
Luster: Vitreous
Streak: White
Density: 3.53-3.6
Cleavage: Good on {100}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Surinamite can be identified by its characteristic greenish-blue color, tabular crystal habit, and high hardness. Its specific occurrence environment – in high-temperature, aluminum-rich metamorphic rocks – is also key. ## Distinguishing from Similar Minerals It can be confused with sapphire, cordierite, or kyanite due to similar color and hardness. Differentiation requires analysis of crystal habit (surinamite is monoclinic, sapphire trigonal, and cordierite and kyanite are orthorhombic and triclinic, respectively) and associated minerals. Precise identification often requires advanced research methods, such as X-ray diffraction. ## Crystal Forms Surinamite crystals are typically tabular or bladed, often elongated. They usually form small, radial or chaotic aggregates within the host rock. Well-formed, single crystals are rarely observed.

Geological environment

## Genesis Surinamite is a metamorphic mineral, forming under granulite and amphibolite facies conditions, i.e., at high temperatures and high pressures. It forms in rocks rich in aluminum (Al) and magnesium (Mg), and poor in silica (SiO₂). ## Mineral Associations It most commonly co-occurs with minerals such as: cordierite, sapphirine, phlogopite, garnet (pyrope), corundum, kyanite, sillimanite, spinel, quartz, and plagioclase. ## Localities Aside from the type locality in the Bakhuis Mountains in Suriname, surinamite has been identified in only a few other places worldwide. These include, among others, the Casey Mountains in Enderby Land (Antarctica), the Fianarantsoa area in Madagascar, the Arusha and Dodoma regions in Tanzania, and in Zambia.

Rarity

Very rare

For collectors

## Quality Criteria Most valued by collectors are specimens with well-formed, intensely colored surinamite crystals that contrast with the lighter host rock. Due to its rarity, any specimen with visible and well-identified crystals is considered valuable. Crystal size and transparency significantly increase the attractiveness of a specimen. ## Popular Localities Specimens from the type locality in Suriname are historically most important, but they appear extremely rarely on the collector's market. Most available specimens come from Tanzania, which provides material with relatively good crystal development.

Care and storage

## Cleaning Surinamite specimens should only be cleaned mechanically, using a soft, dry brush to remove dust. Due to its occurrence as small inclusions in the host rock, wet cleaning is not recommended to avoid damaging surrounding minerals. ## What to Avoid Avoid contact with chemicals, especially strong acids and bases. Despite its high hardness, the mineral is brittle, so it should be protected from impacts and sudden temperature changes. ## Storage Collector specimens of surinamite are best stored in stable conditions, in closed display boxes, protecting them from dust and mechanical damage. It is advisable to isolate them from other minerals to prevent scratching.

Sources

IMA Mineral List (CNMNC)