Rémondite-(La)

Chemical formula: Na₃(La,Ca,Na)₃(CO₃)₅

Rémondite-(La) is a rare mineral from the burbankite group, distinguished by its intense, bright yellow color and occurrence in alkaline massifs.

## Characteristics Rémondite-(La) is a complex sodium and lanthanum carbonate, belonging to the burbankite group. It forms small, tabular or prismatic crystals, often gathered in radial or granular aggregates. Its most characteristic feature is its intense, bright yellow to yellowish-orange color, which makes it recognizable. Specimens are usually small, and well-formed crystals are rare. ## Physical Properties This mineral is characterized by a hardness of 3 on the Mohs scale, making it relatively soft. It is transparent, and its luster is described as vitreous. The density is approximately 3.5 g/cm³, which is a relatively high value for a carbonate. ## Colors and Varieties The dominant and essentially only known color of rémondite-(La) is bright yellow to yellowish-orange. No color or commercial varieties are distinguished. ## History and Name The mineral's name honors the French rare mineral collector, Georges Rémond (born 1930). The suffix "-(La)" indicates the dominance of lanthanum as a rare earth element in its chemical composition. It was first described in 1987 by G. Della Ventura, G.C. Parodi, and C.M. Williams based on material from Mont Saint-Hilaire in Canada, although the Koashva open pit in Russia is considered the type locality. ## Applications Due to its extreme rarity and small crystal sizes, rémondite-(La) has no industrial applications. It is solely an object of interest for specialized rare mineral collectors and scientists.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
White
Density
3.5
Fracture
Conchoidal
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification The key diagnostic feature is its bright yellow color combined with its specific occurrence environment (pegmatites in alkaline massifs). Its low hardness (3 on the Mohs scale) and white streak are also helpful in identification. However, final confirmation requires advanced chemical analyses (EDS) to confirm the presence of sodium and lanthanum. ## Distinguishing from Similar Minerals It can be confused with other yellow secondary minerals occurring in similar parageneses, such as some zeolites or other rare earth carbonates. It differs from them in crystal form and, most importantly, chemical composition. ## Crystal Forms It crystallizes in the monoclinic system. It most often forms small, tabular crystals with a hexagonal outline, as well as short prisms. It occurs mainly as granular aggregates or small, radial aggregates filling voids in the rock.

Geological environment

## Genesis Rémondite-(La) is a hydrothermal mineral, associated with the late stages of pegmatite crystallization within diversified alkaline massifs and carbonatites. It forms in voids and fissures, crystallizing from solutions rich in sodium, carbonates, and rare earth elements. ## Mineral Associations In its type locality (Koashva, Russia), it co-occurs with natrite, shortite, vitusite-(Ce), and lomonosovite. At Mont Saint-Hilaire (Canada), it is accompanied by ancylite-(Ce), microcline, aegirine, natrolite, catapleiite, and sérandite. ## Localities This is an extremely rare mineral, known from only a few locations worldwide. The most important ones include: - Russia: Koashva open pit on the mountain of the same name, Kola Peninsula, Murmansk Oblast (type locality). - Canada: Poudrette Quarry, Mont Saint-Hilaire, Quebec. - Greenland: Ilimaussaq alkaline complex.

Rarity

Very rare

For collectors

## Quality Criteria The most highly prized rémondite-(La) specimens are those with well-formed, sharp crystals of intense, bright yellow color. Transparency and aesthetic placement on the rock matrix, preferably accompanied by contrasting associated minerals, are important. Due to its rarity, even microscopic but well-defined crystals are considered valuable. ## Popular Localities Specimens from the two classic localities for rare minerals, Mont Saint-Hilaire in Canada and the massifs of the Kola Peninsula in Russia, are by far the most sought after by collectors. Specimens from these locations are considered the best in terms of quality and crystal development.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its rarity and potential reactivity, contact with water and chemical agents should be avoided. If liquid is necessary, pure isopropyl alcohol is recommended, followed by immediate drying. ## What to Avoid The mineral is soft and susceptible to scratches. Avoid contact with harder minerals, ultrasound, and any acids that could damage it. Protect it from sudden temperature changes. ## Storage The safest way to store specimens is to place them in a sealed display box, away from dust, moisture, and direct sunlight. It is advisable to isolate it from other minerals to prevent mechanical damage.

External references

Sources

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