Juangodoyite

Chemical formula: Na₂Cu₂+(CO₃)₂

Juangodoite is a rare, blue sodium copper carbonate, forming microscopic, tabular crystals.

## Characteristics Juangodoite is a very rare mineral from the carbonate group, chemically a hydrated sodium copper carbonate. It occurs as extremely small, tabular or bladed crystals, rarely exceeding 0.2 mm in length. These crystals form rosette-like or radial aggregates, as well as thin coatings and crusts on rock surfaces. Due to the microscopic size of the crystals, its visual features are difficult to observe without specialized equipment. ## Physical Properties Juangodoite crystals exhibit a vitreous luster. They are transparent to translucent. The hardness on the Mohs scale is low, at 2, which means it is a very soft mineral. The density calculated based on the chemical formula and unit cell parameters is 3.33 g/cm³. ## Colors and Varieties This mineral is characterized by an intense, blue color in various shades, from light blue to dark blue. No varieties have been distinguished. ## History and Name Juangodoite was discovered in the Santa Rosa mine in the Atacama region of Chile and described in 2005. Its name commemorates Juan Godoy, a Chilean miner who discovered rich silver deposits in Chañarcillo in 1832, initiating the "silver rush" in Chile and significantly impacting the region's development. Approved by the International Mineralogical Association (IMA) in 2004 (IMA2004-032). ## Uses Juangodoite has no industrial application. Its significance is purely scientific and collectible, being a coveted item for collectors specializing in rare minerals or minerals from specific localities (so-called "micromounts").

Properties

Mohs hardness: 2
Luster: Vitreous
Streak: Light blue
Density: 3.33
Cleavage: Perfect on {001}
Fracture: Micaceous
Transparency: Transparent to Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Juangodoite identification is primarily based on its characteristic, intensely blue color, its occurrence as small, rosette-like aggregates, and its origin. A key feature is its reaction to water – this mineral readily dissolves in it. However, definitive identification requires advanced analytical methods such as X-ray diffraction (XRD) or chemical analysis (EDS). ## Distinguishing from Similar Minerals Juangodoite can be confused with other blue secondary copper minerals such as azurite, chalcanthite, or linarite. It differs from azurite by its lighter streak and water solubility (azurite reacts with hydrochloric acid). From chalcanthite, which is also water-soluble, it can be distinguished based on crystal habit and associated minerals. Linarite is significantly harder and does not dissolve in water. ## Crystal Forms Juangodoite forms very small, flattened, tabular or bladed crystals, typically with a hexagonal outline. These crystals often combine into radial or rosette-like aggregates, and also form thin coatings on the host rock.

Geological environment

## Genesis Juangodoite is a secondary mineral formed in the oxidation (supergene) zone of copper ore deposits in extremely arid, desert conditions. Its formation is associated with the interaction of solutions rich in sodium and carbonates with primary copper sulfides. It forms directly on rock surfaces as a result of weathering processes. ## Mineral Associations This mineral occurs in association with other rare secondary minerals. In its type locality (Santa Rosa mine), it was found in association with malachite, chalconatronite, andersonite, baylissite, gypsum, and also with a blue, amorphous copper silicate. ## Localities Juangodoite is an extremely rare mineral, known from only a few locations worldwide. The most important and type locality for its occurrence is the Santa Rosa mine in the Santa Rosa-Huantajaya mining district, Iquique Province, Tarapacá Region (formerly Atacama) in Chile. The best known specimens originate from this site.

Rarity

Very rare

For collectors

## Quality Criteria The quality of juangodoite specimens is primarily assessed based on the richness and aesthetics of the crystal aggregates. Most prized are specimens with clearly formed, undamaged crystal rosettes of intense blue color, contrasting well with the host rock. Due to the microscopic nature of the mineral, all specimens are "micromounts," and their value depends on the abundance and quality of microcrystals visible under magnification. ## Popular Localities The only source of valuable collectible juangodoite specimens is its type locality – the Santa Rosa mine in Chile. Specimens from this location are the standard for this mineral.

Care and storage

## Cleaning Juangodoite specimens must be handled with extreme caution. Due to its water solubility, wet cleaning is absolutely forbidden. Only gentle dust removal with a soft brush or compressed air from a safe distance is permissible. ## What to Avoid Avoid contact with water, acids, and any chemicals that could damage or dissolve it. The mineral is very soft and brittle, making it exceptionally susceptible to mechanical damage. It should be protected from moisture and temperature changes. ## Storage The best way to store juangodoite is to place it in a sealed, airtight "micromount" box, which protects it from dust, moisture, and physical damage. It is advisable to add a desiccant (e.g., silica gel) to the container.

Sources

IMA Mineral List (CNMNC)