Lannonite

Chemical formula: HCa<sub>4</sub>Mg<sub>2</sub>Al<sub>4</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>8</sub>F<sub>9</sub>·32H<sub>2</sub>O

Lannonite is a hydrated aluminum, magnesium, and calcium sulfate, forming microscopic, colorless tabular crystals.

## Characteristics Lannonite is a very rare mineral from the sulfate group. It occurs as extremely small, colorless, tabular crystals, which usually do not exceed 0.2 mm in length. These crystals form rosette-like or spherical aggregates, as well as coatings and crusts. Due to the microscopic size of the crystals, its visual features are difficult to observe without specialized equipment. ## Physical Properties Lannonite crystals exhibit a vitreous luster. They are too small and brittle to practically determine their hardness or density in a standard way. The mineral is transparent to translucent. ## Colors and Varieties Lannonite is colorless. No colored varieties are known. ## History and Name The mineral was discovered at the United Verde Mine in Jerome, Yavapai County, Arizona (USA). Its name honors Robert Michael Lannon (born 1946), an American mineral collector from Agoura, California, who first noticed this mineral. It was described and approved as a new mineral species in 1979 by S.A. Williams. ## Uses Lannonite has no industrial application. It is of purely scientific significance and is of interest to specialized collectors of rare minerals.

Properties

Mohs hardness
1
Luster
Vitreous
Streak
White
Density
2.15
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of lannonite is possible almost exclusively using advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). In collector conditions, identification relies on knowledge of the locality and co-occurring minerals. Its reaction to water is characteristic – it dissolves. ## Distinguishing from Similar Minerals Lannonite can be confused with other secondary sulfates, such as gypsum, chalcanthite, or epsomite, which form similar coatings. It is distinguished from them primarily by its chemical composition and specific, microscopic crystal forms. Unlike many of them, it is colorless. ## Crystal Forms It forms very small, thin, tabular crystals with a hexagonal outline. These crystals often group into rosette-like or spherical aggregates and form thin crusts and coatings on rock surfaces.

Geological environment

## Genesis Lannonite is a secondary mineral, formed as a result of weathering (oxidation) processes of sulfide deposits in arid and desert climates. It forms as a product of mine fires (so-called post-mining mineral), crystallizing from sulfate solutions on the walls of old mine workings. ## Mineral Associations This mineral co-occurs with other secondary sulfates, such as voltaite, rhomboclase, chalcanthite, melanterite, pickeringite, halotrichite, as well as gypsum and native sulfur. ## Localities The only confirmed and described occurrence of lannonite in the world is its type locality – the United Verde Mine in Jerome, Yavapai County, Arizona, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a lannonite specimen depends on the richness of the coating and the degree of development of microscopic crystals in aggregates. Since it is a "micromount" type mineral, specimens are evaluated under a microscope. Samples with clearly visible, rosette-like crystal clusters, contrasting with the rock matrix, are most valued. ## Popular Localities The only source of lannonite specimens is the United Verde Mine in Arizona. Material from this locality is extremely rare and sought after by collectors specializing in secondary and rare minerals.

Care and storage

## Cleaning Lannonite specimens should not be wet cleaned. Due to its solubility in water, contact with it can lead to the destruction of the mineral. Dust can be removed very carefully using a soft brush or a photographic air blower. ## 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 heated or exposed to direct sunlight. ## Storage Lannonite specimens should be stored in a dry place, preferably in tightly sealed containers (so-called "micromount boxes") away from sources of moisture. Stable ambient temperature is crucial for preserving the integrity of the samples.

Sources

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