Dyrnaesite-(La)

Chemical formula: Na₈Ce⁴⁺(La³⁺,REE)₂(PO₄)₆

Dyrnaesite-(La) is a rare, transparent sodium, cerium, and lanthanide phosphate with a pale yellowish-green color, discovered in Greenland.

## Characteristics Dyrnaesite-(La) is a complex sodium, cerium, and lanthanide phosphate belonging to the vitusite group. It forms small, tabular or platy crystals, typically not exceeding 1 mm in size. It occurs as single crystals or small aggregates. It is a transparent mineral with a pale yellowish-green color and a vitreous luster. ## Physical Properties The mineral is characterized by a vitreous luster and a white streak. Its density is approximately 3.68 g/cm³. It is transparent. The exact hardness has not been determined, but for related minerals in its group, it is around 4-5 on the Mohs scale. ## History and Name The mineral's name comes from the former name of the Ilímaussaq complex in Greenland – Dyrnæs – and from the dominant rare-earth element in its composition, lanthanum (La). It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2003 (IMA2003-049). It was described by a team of mineralogists: O.V. Petersen, E.I. Semenov, H.I. Micheelsen, J.G. Rønsbo, and O. Medenbach. ## Applications Due to its extreme rarity and small crystal size, dyrnaesite-(La) has no industrial applications. It is solely of scientific importance and is an object of interest for specialized collectors of rare minerals.

Properties

Luster: Vitreous
Streak: white
Density: 3.68
Fracture: Irregular/Uneven
Transparency: Transparent
Crystal system: Orthorhombic

Diagnostic features

## Identification Practical identification of dyrnaesite-(La) is impossible without advanced analytical methods, such as energy-dispersive spectroscopy (EDS/WDS) to confirm its chemical composition. Preliminary identification is based on its occurrence locality (Ilímaussaq complex), pale yellowish-green color, transparency, and co-occurrence with characteristic associated minerals. ## Distinguishing from Similar Minerals It can be confused with other minerals from the vitusite group, such as vitusite-(Ce) or olgite. Differentiation requires chemical analysis to determine the dominant rare-earth elements and the sodium to other cation ratio. Visually, it is virtually indistinguishable from these minerals. ## Crystal Forms Crystals are typically very small, tabular or platy, exhibiting well-developed {010}, {110}, and {011} faces. They occur as single, isolated crystals or small, loose aggregates.

Geological environment

## Genesis Dyrnaesite-(La) forms in highly alkaline, agpaitic nepheline syenites and their pegmatites. It is a late-stage crystallization mineral, forming in rock cavities and fractures. ## Mineral Associations In its type locality (Ilímaussaq complex), it co-occurs with minerals such as aegirine, analcime, microcline, nepheline, natrolite, eudialyte, steenstrupine-(Ce), vitusite-(Ce), and rare minerals from the lomonosovite group. ## Localities The only confirmed and described occurrence of dyrnaesite-(La) in the world is its type locality – the Taseq slope in the Ilímaussaq alkaline complex, Kujalleq region, southern Greenland.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a specimen primarily depends on its confirmed analytical identity. The most desirable specimens are well-formed, even if microscopic, single crystals with good transparency and visible color. The abundance of associated minerals on the rock matrix is also of great importance. ## Popular Localities The only source of specimens is the Ilímaussaq complex in Greenland. Material from this locality is highly valued by collectors specializing in rare minerals and alkaline pegmatite minerals.

Care and storage

## Cleaning Due to its extreme rarity and potential fragility, mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Avoid ultrasonic cleaners, steam cleaners, acids, and all chemical solvents. The mineral should be protected from sudden temperature changes and direct, prolonged exposure to sunlight. ## Storage Specimens should be stored under stable conditions, preferably in a sealed "micromount" box, to protect them from dust, mechanical damage, and moisture. Display should be away from heat sources and direct light.