Fivegite

Chemical formula: K<sub>4</sub>Ca<sub>2</sub>[AlSi<sub>7</sub>O<sub>17</sub>(O<sub>2-x</sub>(OH)<sub>x</sub>)][(H<sub>2</sub>O)<sub>2-x</sub>(OH)<sub>x</sub>]Cl (x = 0-2)

Fivegite is a very rare mineral from the silicate group, discovered in 2022 in the Vesuvius volcanic complex in Italy.

## Characteristics Fivegite is a mineral with an exceptionally complex chemical composition, belonging to the layered silicates. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2022. It occurs as very small, colorless, tabular crystals, reaching sizes up to 150 micrometers. These crystals form aggregates or appear as single flakes. Due to their microscopic size, its visual features are difficult to assess without specialized equipment. ## Physical Properties Fivegite crystals are transparent and exhibit a white streak. The luster is described as vitreous. The mineral is brittle, and its hardness and density have not yet been precisely measured due to the small amount of available research material. ## Colors and Varieties Fivegite is colorless. No colored or commercial varieties are known. ## History and Name The mineral's name honors five Italian scientists (the "five Gs"): Giovanni Graziani, Giancarlo Parodi, Gianmario Molini, Gianni Guastalla, and Giovanni De Casa, for their contributions to mineralogy and petrology. It was discovered in a sample from the historic 1944 Vesuvius eruption, within volcanic fumaroles. The research team that described the mineral consisted of scientists from Italy and Russia. ## Uses Fivegite has no industrial applications. Its significance is purely scientific and collectible, as a unique and newly discovered mineral species.

Properties

Luster
Vitreous
Streak
White
Cleavage
Perfect on {0001}
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of fivegite is impossible without advanced laboratory techniques. Recognition is based on chemical analysis (EDS) and single-crystal X-ray diffraction (SC-XRD), which allow its unique composition and crystal structure to be determined. Visually, in the form of microscopic, colorless tablets, it is indistinguishable from many other minerals. ## Distinguishing from Similar Minerals Based on visual characteristics alone, fivegite can be confused with many other microminerals found in similar environments, such as other silicates or chlorides. Definitive distinction is only possible through structural and chemical analysis. ## Crystal Forms Fivegite forms thin, tabular or platy crystals with a hexagonal outline, which can occur singly or form small, rosette-like aggregates.

Geological environment

## Genesis Fivegite is a fumarolic mineral. It forms as a result of the sublimation of volcanic gases at high temperatures, in an environment rich in potassium, calcium, aluminum, silicon, and chlorine. It crystallizes directly from the gas phase on the walls of voids within lava. ## Mineral Associations This mineral occurs in association with other fumarolic minerals, such as halite (NaCl), sylvite (KCl), and hematite (Fe₂O₃). It also co-occurs with the newly discovered mineral named thermaerogenite. ## Localities The only confirmed locality of fivegite in the world is its type locality – the Vesuvius volcanic complex, near Naples, Italy. The mineral was found in material from the 1944 eruption.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a fivegite specimen is determined solely by its scientific and documentary value. Since the crystals are microscopic, the most important criterion is the confirmation of their identity by a reputable laboratory. Collectible value is associated with possessing a documented specimen from the type locality. The size and richness of aggregates, although still on a micro scale, can slightly increase the attractiveness of the specimen. ## Popular Localities The only source of specimens is Vesuvius in Italy. The material is extremely difficult to obtain and is available only in specialized collecting circles and scientific institutions.

Care and storage

## Cleaning Due to the extreme rarity and microscopic size of the crystals, fivegite specimens should not be cleaned by any mechanical or chemical means. Any attempt at cleaning risks irreversible damage or loss of the mineral. Specimens should be analyzed and handled only under laboratory conditions. ## What to Avoid Absolutely everything should be avoided: contact with water, chemicals, ultrasound, temperature changes, humidity, and light exposure. The mineral is likely sensitive to atmospheric conditions, and its long-term stability is unknown. ## Storage Fivegite specimens, typically in the form of host rock fragments or microscopic preparations, must be stored in specialized, sealed containers (so-called micromount boxes), under stable room conditions, away from dust, vibrations, and light. The safest place is a dedicated micromineral cabinet.

Sources

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