Freitalite

Chemical formula: C₁₄H₁₀

Freitalite is a naturally occurring anthracene, an organic mineral with blue fluorescence under UV light, found in burning coal dumps.

## Characteristics Freitalite is an organic mineral, a natural, crystalline form of anthracene (C₁₄H₁₀). It occurs as colorless to pale yellow, tabular or platy crystals, often forming thin coatings and crusts. Its most characteristic feature is strong, blue-violet fluorescence under longwave ultraviolet (UV) light. It is a very soft and light mineral. ## Physical Properties Freitalite is characterized by very low hardness, approximately 1 on the Mohs scale, which means it can be scratched with a fingernail. It has a pearly luster on cleavage surfaces and a vitreous luster elsewhere. It is transparent to translucent. Its density is low, about 1.25 g/cm³, which is typical for organic minerals. ## Colors and Varieties This mineral is usually colorless, white, or has a pale yellow hue. No color or commercial varieties are distinguished. ## History and Name The name "freitalite" comes from its discovery locality – a burning coal dump of the "Glück-Auf" mine in Freital, Saxony, Germany. It was first described in 1993, although its synthetic counterpart, anthracene, had been known for a long time. ## Uses Freitalite has no industrial application due to its rarity and small crystal size. It is solely an object of interest for collectors specializing in rare or organic minerals, as well as scientists studying mineral-forming processes in anthropogenic environments.

Properties

Mohs hardness
1
Color
intense violet or whitish-violet to white
Luster
Pearly
Streak
white
Density
1.240
Cleavage
Perfect on {001}
Fracture
Micaceous
Transparency
Transparent,Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification The most important diagnostic feature of freitalite is its intense blue-violet fluorescence under longwave UV light. It is an extremely soft (Mohs hardness 1) and light mineral. It occurs in characteristic environments – on burnt rocks associated with coal fires. ## Distinguishing from Similar Minerals Other mine sublimates, such as native sulfur, ammonium chloride (sal ammoniac), or evenkite, may occur in similar environments. However, sulfur has a characteristic yellow color and does not exhibit such fluorescence. Sal ammoniac is water-soluble. Evenkite, another hydrocarbon, has higher hardness. The key test remains fluorescence under UV light. ## Crystal Forms Freitalite forms very small, thin, tabular crystals with hexagonal or rhombic outlines, often arranged in rosette aggregates, fans, or thin coatings on the surface of the host rock.

Geological environment

## Genesis Freitalite is a mineral of anthropogenic origin. It forms as a result of the sublimation of gases rich in aromatic hydrocarbons during the slow combustion of hard coal in mine dumps. It crystallizes in lower temperature zones (below 200°C) from hot gases escaping through cracks in burnt shales. ## Mineral Associations This mineral co-occurs with other minerals formed under similar conditions, such as native sulfur, ammonium chloride (sal ammoniac), realgar, orpiment, as well as other rare organic minerals. ## Localities The most important and classic localities for this mineral are in Germany, in Saxony (Freital, Zwickau) and in North Rhine-Westphalia (Anna mine in Alsdorf). It has also been reported in burning dumps in Pennsylvania (USA) and in the Czech Republic.

Rarity

Very rare

For collectors

## Quality Criteria The most prized freitalite specimens are those with well-formed, sharp crystals forming aesthetic, rosette aggregates on a contrasting matrix. Crystal size is crucial – specimens with crystals exceeding a few millimeters are exceptionally rare. The intensity of fluorescence is also important. Due to its mode of occurrence, specimens are almost exclusively of the "micromount" type. ## Popular Localities Classic and most sought-after specimens by collectors come from the original locality in Freital and from the Anna mine dump in Alsdorf, Germany. These localities have yielded the best known crystals of this mineral.

Care and storage

## Cleaning Freitalite specimens are extremely delicate and sensitive. Wet cleaning should be avoided. Only very careful dust removal with a soft brush or a stream of compressed air from a distance is permissible. ## What to Avoid Freitalite is very sensitive to heat – it melts at approximately 216 °C. Any organic solvents and chemicals should be avoided. It should be protected from prolonged exposure to direct sunlight, which can cause its degradation. It is brittle and soft, so all physical contact and vibrations should be avoided. ## Storage Specimens should be stored under stable conditions, in closed, padded "micromount" boxes, to protect them from mechanical damage, dust, and humidity changes. Display should be away from heat sources and direct sunlight.

External references

Sources

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