Frankdicksonite

Chemical formula: BaF<sub>2</sub>

Frankdicksonite is a barium fluoride that forms colorless, isometric crystals with a vitreous luster, being the natural analogue of synthetic barium fluoride.

## Characteristics Frankdicksonite is a barium fluoride (BaF₂), the natural analogue of a commonly synthesized material. It typically forms small, well-formed, cubic crystals, reaching up to 1 mm in size. It occurs as single cubes or aggregates thereof. It is colorless and transparent, with a distinct, vitreous luster. Due to its rarity and small crystal size, it is a mineral primarily of scientific and collector interest. ## Physical Properties This mineral is characterized by a hardness of 3 on the Mohs scale, making it relatively soft. Its density is quite high, at 4.83 g/cm³. It exhibits perfect cleavage in three directions, parallel to the {111} faces of an octahedron, which is typical for minerals with a fluorite structure. The luster is vitreous. ## Colors and Varieties Frankdicksonite is naturally colorless. No colored varieties or trade names are known. ## History and Name The mineral was discovered in the Carlin Gold Mine in Eureka County, Nevada, USA. It was described and approved as a new mineral species in 1974. Its name honors Francis "Frank" W. Dickson (1923-2012), a professor of geochemistry at Stanford University, in recognition of his contributions to the study of hydrothermal geochemical processes. ## Uses Frankdicksonite has no industrial applications due to its extreme rarity. Its synthetic counterpart, barium fluoride, however, is an important optical material used in the production of lenses and windows for infrared spectroscopy and as a scintillator for gamma radiation detection.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
White
Density
4.83
Cleavage
Perfect on {111}
Fracture
Uneven
Transparency
Transparent
Crystal system
Cubic

Diagnostic features

## Identification Frankdicksonite is difficult to identify without advanced analytical methods due to its small crystal size and resemblance to other minerals. Key features include its isometric, cubic crystal habit, high density, colorlessness, and occurrence in a specific environment of hydrothermal gold deposits. Reaction to hydrochloric acid can help distinguish it from calcite. ## Distinguishing from Similar Minerals Frankdicksonite can be confused with fluorite (CaF₂), which has a similar habit and cleavage but lower density (approx. 3.2 g/cm³). Halite (NaCl) also forms cubic crystals but is much lighter, water-soluble, and has a salty taste. It is distinguished from calcite (CaCO₃) by its lack of reaction with cold, dilute hydrochloric acid and its crystal habit. ## Crystal Forms This mineral crystallizes in the isometric system, forming simple, well-formed cubes {100}. Crystals are usually small, not exceeding 1 mm, and occur as single individuals or small groups growing on other minerals.

Geological environment

## Genesis Frankdicksonite is a mineral of hydrothermal origin. It forms in the late stages of crystallization in low-temperature, barium-rich ore veins, cutting carbonaceous mudstone and limestone rocks. At the type locality (Carlin mine), it formed at temperatures below 175°C. ## Mineral Associations This mineral is associated with minerals such as quartz, calcite, barite, pyrite, realgar, orpiment, and getchellite. ## Localities The only confirmed and well-documented occurrence of frankdicksonite in the world is its type locality - the Carlin gold mine in Eureka County, Nevada, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a frankdicksonite specimen primarily depends on the size and perfection of the formed crystals. The most valued specimens are those with sharp, transparent cubes, clearly standing out from the rock matrix. Contrast with associated minerals, such as red realgar or yellow orpiment, is also important. Due to its extreme rarity, any well-defined microcrystal is considered valuable. ## Popular Localities The only source of frankdicksonite specimens is the Carlin mine in Nevada, USA. All specimens available on the collector's market originate from this single locality.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its perfect cleavage, ultrasonic cleaners and mechanical cleaning should be avoided. If liquid is necessary, pure distilled water or isopropyl alcohol is recommended, followed by gentle drying. ## What to Avoid Avoid contact with acids, which can react with the mineral. Frankdicksonite is sensitive to thermal shock and mechanical damage due to its softness and perfect cleavage. It should not be heated or exposed to rapid temperature changes. ## Storage Frankdicksonite specimens, typically small and fragile, should be stored in sealed "micromount" boxes to protect them from dust and mechanical damage. They should be kept away from harder minerals that could scratch them.

External references

Sources

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