Arsenogorceixite

Chemical formula: BaAl₃As₅+O₄(As₅+O₃OH)(OH)₆

Arsenogorceixite is a rare arsenate from the alunite-jarosite supergroup, forming tiny, vitreous crystals ranging from colorless to pale yellow.

## Characteristics Arsenogorceixite is an arsenate mineral belonging to the alunite-jarosite supergroup. It occurs as very small, tabular or pseudocubic crystals, rarely exceeding 0.5 mm. These crystals are typically colorless, white, or pale yellow and exhibit a vitreous luster. ## Physical Properties This mineral is relatively soft, with a hardness of approximately 4.5 on the Mohs scale. It is transparent to translucent. Its density is about 3.76 g/cm³. ## History and Name The name arsenogorceixite refers to its chemical composition – the dominance of arsenic – and its structural relationship with gorceixite. It was first described by D.I. Belakovskiy, M.D. Dyaroov, and V.A. Muftakhov in 1991, based on material from the Kara-Tash mountains in western Uzbekistan.

Properties

Mohs hardness: 4.5
Luster: Vitreous
Streak: White
Density: 3.76
Cleavage: Good on {0001}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Trigonal

Diagnostic features

## Identification Identification of arsenogorceixite requires advanced analytical methods, such as X-ray spectroscopy (EDS/WDS) to confirm its chemical composition (presence of barium, aluminum, and arsenic). Visually, it is practically impossible to distinguish from other minerals in its group without specialized equipment. ## Distinguishing from Similar Minerals It can be confused with other minerals from the alunite-jarosite supergroup, such as arsenogoyazite, gorceixite, or philipsbornite. The differences between them are mainly based on chemical composition, especially the dominant cation in a specific structural position. ## Crystal Forms It forms very small, tabular crystals with hexagonal or trigonal outlines, as well as pseudocubic and rhombohedral crystals. It typically occurs as single, scattered crystals on the surface of the host rock.

Geological environment

## Genesis Arsenogorceixite is a secondary mineral, forming in the oxidation (weathering) zones of arsenic-rich ore deposits. It forms in an acidic environment, as a result of the interaction of arsenic-bearing solutions with aluminosilicate and barium-bearing minerals. ## Mineral Associations It co-occurs with other secondary minerals of the oxidation zone, such as quartz, olivenite, conichalcite, agardite, beudantite, segnitite, arsenogoyazite, and pharmacosiderite. ## Localities The most important localities for this mineral include the Clara mine in the Black Forest (Germany), where it occurs in the form of well-developed microcrystals. Other known localities include the Kara-Tash mountains in Uzbekistan (type locality), the Cap Garonne mine in France, and some deposits in Greece and Switzerland.

Rarity

Very rare

For collectors

## Quality Criteria For micromineral collectors, the most desirable specimens are those with sharp, well-formed, and isolated crystals that contrast with the matrix. Crystal size, although always small, is also important – larger specimens (above 0.2 mm) are more valued. The aesthetics of the entire sample and the presence of rare associated minerals are also important.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the small size of the crystals and their fragility, contact with water and brushes should be avoided. ## What to Avoid Avoid all chemicals, especially acids, which can damage the mineral. The crystals are fragile and susceptible to mechanical damage. Do not heat or clean in ultrasonic cleaners. ## Storage Arsenogorceixite specimens, as microminerals, should be stored in specialized "micromount" boxes that protect them from dust, moisture, and mechanical damage.

Sources

IMA Mineral List (CNMNC)