Cannonite

Chemical formula: Bi<sup>3+</sup><sub>2</sub>O(S<sup>6+</sup>O<sub>4</sub>)(OH)<sub>2</sub>

Cannonite is a rare, secondary bismuth mineral, forming colorless to white, prismatic crystals with a vitreous luster.

## Characteristics Cannonite is a hydroxylated bismuth oxide sulfate. It occurs as small, prismatic or acicular crystals, which can form radial aggregates or fibrous masses. Individual crystals rarely exceed 1 mm in length. It is a colorless to white mineral with a vitreous luster. ## Physical Properties Cannonite has a Mohs hardness of approximately 4. It is a relatively dense mineral, which is typical for bismuth minerals. Crystals are transparent to translucent. It exhibits perfect cleavage in one direction. ## Colors and Varieties This mineral is usually colorless or white. No colored or commercial varieties have been identified. ## History and Name Cannonite was discovered in the Tunnel Extension No. 2 mine in the Marysvale area, Utah, USA. It was described in 1993. The mineral is named in honor of Benjamin Bartlett Cannon V (1950–), an American micromineralogist and collector, who first found the mineral. ## Uses Due to its rarity and small crystal size, cannonite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or microminerals.

Properties

Mohs hardness
4
Luster
Vitreous
Streak
White
Density
5.66
Cleavage
Perfect on {100}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Cannonite can be identified by its form – it creates small, colorless, prismatic or acicular crystals, often in radial aggregates. Its vitreous luster and occurrence in the oxidation zones of bismuth deposits are characteristic. Due to the small size of the crystals, identification usually requires magnification. ## Distinguishing from Similar Minerals It can be confused with other secondary sulfates, such as gypsum or anglesite, but it differs from them in its environment of occurrence (associations with bismuth minerals) and crystal habit. Final differentiation from other rare bismuth sulfates, such as bismuthinite, requires advanced analytical methods (XRD, EDS). ## Crystal Forms Crystals are elongated, prismatic, or acicular. They often form radial, stellate, or fibrous aggregates. Less commonly, they occur as single, well-formed crystals.

Geological environment

## Genesis Cannonite is a secondary mineral, forming in the oxidation (weathering) zones of ore deposits rich in bismuth. It forms as a result of the reaction of sulfate-rich waters with primary bismuth minerals, such as bismuthinite. ## Mineral Associations It most commonly co-occurs with other secondary bismuth minerals. In the type locality (Marysvale, Utah), it has been found in association with quartz, pyrite, bismuthinite, anglesite, covellite, gypsum, jarosite, and osarizawaite. ## Localities The most important and well-documented cannonite localities worldwide include: - Tunnel Extension No. 2 Mine, Marysvale, Utah, USA (type locality). - Gold-Hund Mine, Sankt Christoph, Baden-Württemberg, Germany. - Clara Mine, Wolfach, Black Forest, Germany. - Schmiedestollen Mine, Wittichen, Black Forest, Germany.

Rarity

Very rare

For collectors

## Quality Criteria Specimens with well-formed, sharp, and transparent crystals, forming aesthetic, radial aggregates, are most valued by collectors. Contrast with the rock matrix and the presence of associated minerals are important. Due to the small size of the crystals, specimens are evaluated under a microscope. ## Popular Localities Specimens from the type locality in Marysvale (USA) and from the Clara mine in Germany are most sought after by collectors specializing in microminerals.

Care and storage

## Cleaning Cannonite specimens should be cleaned with the utmost care, using compressed air to remove dust. Due to its reactivity with water, wet cleaning should be avoided. If absolutely necessary, isopropyl alcohol can be used, and the specimen should be dried immediately. ## What to Avoid Contact with water, acids, and other chemicals must be strictly avoided. The mineral is sensitive to changes in humidity and temperature. It should not be exposed to direct sunlight. ## Storage It is recommended to store cannonite in tightly sealed containers (such as "membrane boxes" or sealed boxes) away from sources of moisture. It is best kept under stable temperature conditions, in a dark place.

Sources

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