Demartinite

Chemical formula: K₂SiF₆

Demartinite is a rare potassium fluorosilicate, forming colorless, transparent crystals in volcanic environments.

## Characteristics Demartinite is a potassium fluorosilicate, occurring as small, well-formed crystals. Typical specimens are colorless and transparent, often forming hexagonal prisms or tabular crystals. Due to its origin, it is most commonly found as small coatings and crystalline druses on volcanic rocks. ## Physical Properties This mineral is characterized by a vitreous luster. It is transparent. Its density is approximately 2.85 g/cm³. ## Colors and Varieties Demartinite is usually colorless. No colored varieties are distinguished. ## History and Name The mineral was named in honor of Prof. Francesco Demarto (born 1939), an Italian chemist from the University of Palermo, for his contributions to research on fluorine compounds. It was approved as a new mineral by the International Mineralogical Association (IMA) in 2006. ## Applications Demartinite has no industrial applications. It is of purely scientific and collector's interest.

Properties

Luster
Vitreous
Streak
White
Density
2.85
Transparency
Transparent
Crystal system
Hexagonal

Diagnostic features

## Identification Demartinite is identified based on its specific occurrence environment (volcanic fumaroles), colorless, transparent crystals with a hexagonal habit, and co-occurrence with other fluorides. Confirmation requires advanced analytical methods. ## Distinguishing from Similar Minerals It can be confused with other colorless fumarolic minerals, such as hieratite or malladrite. Distinguishing it based on visual features is very difficult and usually requires chemical or crystallographic analysis. Its water solubility is a distinguishing feature from many silicates. ## Crystal Forms It forms small, hexagonal crystals with a tabular or short-prismatic habit. It occurs as single crystals, small groups, and coatings and crystalline druses.

Geological environment

## Genesis Demartinite is a fumarolic mineral. It forms by sublimation from fluorine and silicon-rich volcanic gases, at temperatures of approximately 150-200°C. It crystallizes directly on rock surfaces near volcanic exhalations. ## Mineral Associations It most commonly co-occurs with other fumarolic minerals, such as hieratite, malladrite, and also native sulfur. ## Localities The only confirmed and described locality (type locality) of this mineral is the La Fossa crater on Vulcano Island (Aeolian Islands) in Italy.

Rarity

Very rare

For collectors

## Quality Criteria The most valued demartinite specimens are those with well-formed, sharp, and transparent crystals, forming rich druses on a small rock matrix. Due to its rarity, any well-documented specimen from the type locality is valuable for specialized collectors. ## Popular Localities The only source of collector's specimens is the type locality – La Fossa crater on Vulcano Island in Italy.

Care and storage

## Cleaning Due to the small size and fragility of the crystals, mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Contact with water and any chemicals should be avoided. ## What to Avoid Contact with water should be avoided, as the mineral is soluble in it. It should be protected from moisture, high temperatures, and all chemical agents. Specimens are very delicate and susceptible to mechanical damage. ## Storage It is recommended to store specimens in sealed, dry "membrane boxes" or in specialized collector's boxes that protect against moisture, dust, and mechanical damage. Exposure to open air should be avoided.

External references

Sources

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