Nyerereite

Chemical formula: Na₂Ca(CO₃)₂

Nyerereite is a rare sodium calcium carbonate, known for its occurrence in the unique carbonatite lavas of the Ol Doinyo Lengai volcano in Tanzania.

## Characteristics Nyerereite is a carbonate mineral, chemically a double carbonate of sodium and calcium. It is extremely rare, and its most famous locality is the active Ol Doinyo Lengai volcano in Tanzania. It forms small, tabular or bladed crystals, often aggregated into radial clusters or forming granular masses. Fresh nyerereite is colorless to white, but due to its instability in atmospheric conditions, it quickly alters, becoming white and losing its transparency. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of 3. It has a vitreous luster, which dulls with weathering. It is transparent to translucent. Its density is approximately 2.54 g/cm³. It is brittle and easily damaged mechanically. ## Colors and Varieties Nyerereite is typically colorless, white, or grayish. No color varieties or commercial names are distinguished. The change in color and appearance is most often a result of its rapid alteration (weathering) due to atmospheric moisture. ## History and Name The mineral was first described in 1963 by J.B. Dawson. Its name honors Julius Nyerere (1922-1999), the first president of Tanzania, the country where the only significant occurrence of this mineral – the Ol Doinyo Lengai volcano – is located. ## Uses Nyerereite has no industrial applications. Its significance is purely scientific and collectible, as a component of globally unique carbonatite lavas.

Properties

Mohs hardness: 3
Color: Colourless
Luster: Vitreous
Streak: White
Density: 2.41
Cleavage: Good on {010}, imperfect on {100} and {001}
Fracture: Uneven
Transparency: Transparent
Crystal system: Orthorhombic

Diagnostic features

## Identification A key diagnostic feature of nyerereite is its instability under atmospheric conditions. A freshly collected, transparent mineral becomes white, cloudy, and brittle within a few hours or days. It reacts violently with acids, releasing carbon dioxide. Its occurrence is practically limited to one location in the world. ## Distinguishing from Similar Minerals Nyerereite co-occurs with another rare carbonate, gregoryite, which is even more unstable. In its weathered form, it may resemble calcite or other white carbonates, but its genesis and extreme instability are unique. It differs from calcite by its lower hardness and specific formation environment. ## Crystal Forms It forms pseudohexagonal, tabular or bladed crystals, often arranged in radial aggregates. It also occurs as granular masses and as a component of rock (carbonatite).

Geological environment

## Genesis Nyerereite is a mineral of magmatic origin. It crystallizes directly from unique, low-temperature (approximately 500-600°C) natrocarbonatite lava, which is a product of the eruption of the Ol Doinyo Lengai volcano in Tanzania. This is the only active volcano in the world that emits this type of lava. ## Mineral Associations This mineral occurs in close association with gregoryite, which is the dominant component of fresh carbonatite lava. It is also accompanied by sylvite, halite, fluorapatite, magnetite, and minerals from the phlogopite group. ## Localities The only confirmed and significant locality for nyerereite in the world is the Ol Doinyo Lengai volcano, located in the East African Rift Valley in northern Tanzania.

Rarity

Very rare

For collectors

## Quality Criteria The most desired specimens by collectors are fresh ones, retaining transparency and original crystalline form. Due to the extreme instability of the mineral, such specimens are almost impossible to obtain and maintain outside specialized laboratories. Collections mainly feature pseudomorphs after nyerereite or specimens that have already altered, losing their original appearance. Its value is primarily scientific and documentary, as a sample from such a unique locality. ## Popular Localities The only source of collectible specimens is the Ol Doinyo Lengai volcano in Tanzania. Obtaining material is very difficult and dangerous due to volcanic activity.

Care and storage

## Cleaning Nyerereite specimens must absolutely not be cleaned wet. Contact with water, even in the form of water vapor, leads to its rapid decomposition. Only very careful, mechanical removal of dust with a soft brush or a stream of compressed air from a distance is permissible. ## What to Avoid Above all, moisture and water should be avoided. The mineral is hygroscopic and readily absorbs water from the environment, causing its chemical transformation into other, more stable minerals (e.g., pirssonite, gaylussite). It should be protected from temperature changes, direct sunlight, and all chemicals. ## Storage Storing nyerereite is very difficult and requires special conditions. The best solution is to keep specimens in hermetically sealed containers (e.g., "perky box" type) along with a desiccant (e.g., silica gel). Some collectors store it immersed in paraffin or mineral oil to cut off access to air and moisture.