Earlandite

Chemical formula: Ca₃(C₆H₅O₇)³⁻₂·₄H₂O

Earlandite is a hydrated calcium citrate, a rare organic mineral forming microscopic, colorless or pale yellow spherulitic aggregates.

## Characteristics Earlandite is a mineral from the organic substances group, and chemically, it is a hydrated calcium citrate. It occurs as very small, spherical aggregates (spherulites) or rosette-like clusters, rarely exceeding 0.5 mm in diameter. Individual crystals forming the aggregates are in the form of tiny, elongated laths. Due to its size, it is a mineral observable mainly under a microscope. ## Physical Properties Earlandite crystals are too small to precisely determine their hardness or cleavage. The mineral's density is approximately 1.80 g/cm³. It is translucent and exhibits a weak, vitreous luster. ## Colors and Varieties This mineral is typically colorless, white, or pale yellow. No color varieties or commercial varieties are distinguished. ## History and Name Earlandite was first described in 1936 by Francis Bannister. The mineral's name honors Arthur Earland, a British micropaleontologist who discovered it in samples of concretions from the seabed of the Weddell Sea off the coast of Antarctica. The type locality is 71°22'S; 16°34'W, Weddell Sea, West Antarctica. ## Uses Earlandite has no industrial application. Its significance is purely scientific and collectible, as an example of a rare mineral of organic origin.

Properties

Luster: Vitreous
Density: 1.80
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of earlandite is possible almost exclusively by analytical methods, such as X-ray diffraction (XRD) or spectroscopy. Visually, under high magnification, characteristic spherulitic or rosette-like aggregates composed of tiny, lath-like crystals can be observed. Its occurrence in deep-sea sediments or within concretions is also a diagnostic clue. ## Distinguishing from Similar Minerals Due to its appearance and small size, it can be confused with other secondary minerals forming similar coatings, e.g., some zeolites or carbonates. Certain differentiation requires specialized research equipment. Unlike carbonates, earlandite does not react with hydrochloric acid. ## Crystal Forms Earlandite forms spherulites, which are spherical aggregates with a radial internal structure. These aggregates consist of very fine, elongated, lath-like crystals. Single, well-formed crystals are extremely rare and microscopic in size.

Geological environment

## Genesis Earlandite is an organic mineral, formed as a result of diagenetic processes in marine sediments. It forms in a low-temperature environment, likely with the involvement of organic matter. At the type locality (Weddell Sea), it was found within and on the surface of clayey-sandy concretions recovered from a depth of approximately 2590 meters. ## Mineral Associations This mineral has been found in association with gypsum and unidentified clay minerals within sedimentary concretions. ## Localities Apart from the type locality in Antarctica, earlandite has been identified in sediments of the Tyrrhenian Sea in Italy. It is an extremely rare mineral and known from only a few locations worldwide.

Rarity

Very rare

For collectors

## Quality Criteria As a "micromount" type mineral, the collectible value of earlandite depends on the quality and richness of the aggregates on the matrix. Specimens with clearly formed, numerous spherulites that contrast with the substrate are most valued. It is important that the delicate structures are undamaged. Due to its rarity, every analytically confirmed specimen has high scientific and collectible value. ## Popular Localities The only source of specimens available on the collector's market, though still extremely rare, is the type locality in the Weddell Sea, Antarctica.

Care and storage

## Cleaning Earlandite specimens are extremely delicate and small. They usually occur as coatings or small clusters on other material (matrix) and should not be mechanically cleaned. Any physical contact, even with a soft brush, can destroy the microscopic crystals. If dust removal is necessary, a gentle stream of compressed air can be used from a safe distance. ## What to Avoid Contact with water and all chemicals, including acids and bases, which can dissolve it, must be strictly avoided. The mineral is sensitive to changes in temperature and humidity. It should not be heated or exposed to direct sunlight. ## Storage Specimens should be stored under stable conditions, in closed, airtight containers (e.g., "micromount" type), which protect them from dust, humidity, and mechanical damage. It is best to keep them in a dry place, away from heat and light sources.