Joteite

Chemical formula: Ca₂Cu₂+Al(As₅+O₄)[As₅+O₃(OH)]₂(OH)₂·₅H₂O

Joteite is a very rare, blue-green calcium, copper, and aluminum arsenate, forming microscopic, tabular crystals.

## Characteristics Joteite is a hydrated calcium, copper, and aluminum arsenate, occurring as very small, thin, tabular crystals not exceeding 0.2 mm in size. These crystals form rosette-like or radial aggregates, as well as spherical clusters. Due to the microscopic size of the crystals, the visual features of individual specimens are difficult to observe without specialized equipment. ## Physical Properties Joteite crystals exhibit blue-green pleochroism. The hardness of the mineral has not been precisely determined but is estimated to be around 3 on the Mohs scale. The luster is vitreous. It is a brittle mineral. ## Colors and Varieties Joteite has a characteristic blue-green color. No varieties have been distinguished. ## History and Name The mineral was discovered in the Jote mine, in the Atacama region of Chile, from which its name is derived. It was approved by the International Mineralogical Association (IMA) in 2012 under number 2012-033. It was first described by Anthony R. Kampf and co-authors in 2013. ## Uses Joteite has no industrial application. Its significance is purely scientific and as a collector's item, being a very rare and recently discovered mineral.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: Pale blue-green
Density: 3.19
Cleavage: Perfect on {001}
Fracture: Brittle
Transparency: Translucent
Crystal system: Triclinic

Diagnostic features

## Identification Identification of joteite is possible almost exclusively through advanced analytical methods, such as Raman spectroscopy, X-ray diffraction (XRD), and chemical analysis (EDS/WDS). In collector's conditions, recognition is based on its characteristic blue-green color, the form of microscopic, tabular crystals forming rosette-like aggregates, and knowledge of the locality (Jote mine). ## Differentiation from Similar Minerals Joteite can be confused with other secondary copper and arsenic minerals of similar color, such as olivenite, conichalcite, or agardite. Differentiation requires specialized studies, as joteite is the only known arsenate containing calcium, copper, and aluminum simultaneously. Chemical analysis of the elemental composition is crucial. ## Crystal Forms Joteite crystallizes as very thin, tabular crystals, flattened parallel to the {001} plane. These crystals combine into characteristic, rosette-like or radial aggregates, and also form small, spherical clusters.

Geological environment

## Genesis Joteite is a secondary mineral, forming in the oxidation zones (gossans) of polymetallic deposits rich in arsenic and copper, under desert climate conditions. It forms as a result of the alteration of primary ore minerals, such as enargite. ## Mineral Associations This mineral occurs in association with other rare secondary minerals. At its type locality (Jote mine), it was found in association with quartz, barite, jarosite, alunite, chalcanthite, antlerite, brochantite, atacamite, as well as other arsenates such as chenevixite, scorodite, mansfieldite, lavendulan, and pushcharovskite. ## Localities The only confirmed occurrence of joteite in the world is its type locality – the Jote mine, located approximately 35 km south of the city of Copiapó in the Atacama region, northern Chile.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, joteite is primarily valued by collectors specializing in "micromount" specimens. The most highly prized specimens are those that display well-formed, undamaged, rosette-like crystal aggregates of intense, blue-green color. Contrast with the rock matrix and the richness of association with other rare minerals are also important. ## Popular Localities The only source of joteite specimens is the Jote mine in Chile. Material from this locality is extremely rare on the collector's market.

Care and storage

## Cleaning Joteite specimens are extremely delicate and usually consist of microscopic crystals on a rock matrix. Mechanical or chemical cleaning is not recommended. Any attempts at cleaning may irreversibly destroy the fragile structure of the aggregates. It is safest to leave the specimen in its untouched state. ## What to Avoid Contact with water, acids, bases, and other chemicals should be strictly avoided. The mineral is sensitive to changes in temperature and humidity. It should not be heated or exposed to direct sunlight. Vibrations and impacts can cause the delicate aggregates to disintegrate. ## Storage Joteite specimens should be stored in stable conditions, preferably in closed, padded "micromount" boxes that protect against dust, humidity, and mechanical damage. Display should be in sealed display cases, away from sources of heat and light.

Sources

IMA Mineral List (CNMNC)