Meierite

Chemical formula: Ba₄₄Si₆₆Al₃₀O₁₉₂Cl₂₅(OH)₃₃

Meierite is an extremely rare zeolite group mineral, discovered in Norway, forming colorless, tabular crystals.

## Characteristics Meierite is an exceptionally rare mineral belonging to the zeolite group. It was identified in the Larvik alkaline rock complex in Norway. It forms very small, colorless, tabular crystals, reaching sizes up to 0.2 x 0.2 x 0.02 mm. These crystals are usually gathered in small, radial aggregates. Due to its extreme rarity and microscopic size, it is a mineral of purely scientific and collector's interest. ## Physical Properties Meierite crystals exhibit a vitreous luster. They are transparent and colorless. The Mohs hardness is estimated at approximately 4.5. The density calculated based on the formula and unit cell parameters is 2.85 g/cm³. ## History and Name The mineral was approved by the International Mineralogical Association (IMA) in 2009 under number IMA2009-068. Its name honors Professor Walter M. Meier (1926–2009) from the Swiss Federal Institute of Technology Zurich (ETH Zürich) in Switzerland, in recognition of his fundamental contributions to the chemistry and crystallography of zeolites.

Properties

Mohs hardness: ~4.5
Luster: Vitreous
Streak: White
Density: 2.85
Cleavage: None
Fracture: Uneven
Transparency: Transparent
Crystal system: Tetragonal

Diagnostic features

## Identification Identification of meierite is impossible without advanced analytical techniques, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). Visually, at the occurrence site, it can be suspected as microscopic, colorless, tabular crystals in cavities of nepheline syenite. ## Distinguishing from Similar Minerals Distinguishing it from other colorless zeolites or secondary minerals occurring in the same environment (e.g., analcime, natrolite) is possible only through laboratory analysis. ## Crystal Forms Meierite forms thin, tabular crystals with a hexagonal or octagonal outline. They occur as single, very small plates or, more commonly, as radial aggregates.

Geological environment

## Genesis Meierite forms under hydrothermal conditions in the late stage of nepheline syenite crystallization. It crystallizes in small voids and cavities in the rock, as one of the last minerals. ## Mineral Associations At the type locality (Tvedalen, Norway), meierite is associated with aegirine, albite, analcime, catapleiite, microcline, natrolite, and nepheline. ## Localities The only confirmed occurrence of meierite in the world is its type locality: the nepheline syenite quarry in Tvedalen, within the Larvik plutonic complex, Vestfold region, Norway.

Rarity

Extremely rare

For collectors

## Quality Criteria Due to its extreme rarity and microscopic nature, every analytically confirmed meierite specimen is extremely valuable from a scientific point of view. For collectors specializing in systematic minerals or "micromounts," any specimen with well-formed, even the smallest, crystals, embedded on an aesthetic rock matrix and associated with other minerals, will be valuable.

Care and storage

## Cleaning Due to its microscopic size and extreme rarity, meierite specimens should not be cleaned by any mechanical or chemical means. Any attempt at cleaning risks irreversible damage or loss of the mineral. ## What to Avoid Avoid contact with any chemicals, ultrasound, and sudden temperature changes. The mineral is likely sensitive to acids. It should be protected from dust and moisture. ## Storage Meierite specimens should be stored exclusively in specialized, sealed "micromount" containers, protecting them from mechanical damage, dust, and humidity changes. Display is only possible under a microscope.

Sources

IMA Mineral List (CNMNC)