Kemmlitzite

Chemical formula: SrAl₃(As₅+O₄)(S₆+O₄)(OH)₆

Kemmlitzite is a rare strontium and aluminum arsenate and sulfate, forming small, white or colorless tabular crystals.

## Characteristics Kemmlitzite is a complex mineral from the alunite supergroup, being a strontium and aluminum arsenate and sulfate. It occurs as very small, tabular or platy crystals with a hexagonal outline, rarely exceeding 0.1 mm. These crystals often form rosette-like or radial aggregates, as well as earthy or powdery coatings and clusters. Due to the small size of the crystals, its macroscopic features are difficult to observe without magnification. ## Physical Properties Kemmlitzite crystals exhibit a vitreous to pearly luster, especially on cleavage surfaces. It is a relatively soft mineral, with a Mohs hardness of approximately 3.5. It is transparent to translucent. The calculated density is approximately 3.68 g/cm³. ## Colors and Varieties Kemmlitzite is typically colorless or white, sometimes with a yellowish or grayish tint. No colored or commercial varieties are distinguished. ## History and Name 1967 by Hak, Johan & Kvaček first described the mineral. Its name comes from the discovery locality – a quartz-topaz deposit near the town of Kemmlitz in Saxony, Germany. It was approved by the International Mineralogical Association (IMA) in the same year. ## Uses Kemmlitzite has no industrial application. It is of purely scientific and collecting interest, being an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 3.5
Luster: Vitreous, Pearly
Streak: White
Density: 3.68
Cleavage: Perfect on {0001}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Trigonal

Diagnostic features

## Identification Amateur identification of kemmlitzite is practically impossible due to the microscopic size of the crystals. Recognition requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS) to confirm the presence of strontium, aluminum, arsenic, and sulfur in appropriate proportions. Visually, it can be suspected in the form of small, white, tabular crystals in a characteristic geological environment. ## Distinguishing from Similar Minerals It can be confused with other minerals from the alunite supergroup, such as hinsdalite, svanbergite, or woodhouseite, which form similar crystals and occur in similar parageneses. Definitive differentiation is only possible based on chemical analysis, which will show the dominance of strontium and the presence of both arsenate and sulfate groups. ## Crystal Forms Kemmlitzite crystallizes as small, thin, tabular crystals with a hexagonal or pseudohexagonal outline. These crystals often combine into rosette-like, radial, or spherulitic aggregates. It also occurs in the form of earthy and powdery clusters.

Geological environment

## Genesis Kemmlitzite is a secondary mineral, forming in the oxidation (weathering) zones of ore deposits, especially those rich in arsenic. It forms as a result of the interaction of sulfate- and arsenate-rich solutions with rocks containing aluminum and strontium. Its formation is often associated with low-temperature hydrothermal processes. ## Mineral Associations This mineral co-occurs with other secondary arsenates and sulfates. In the type locality (Kemmlitz, Germany), it was found in association with quartz, topaz, kaolinite, goethite, hematite, and zunyite. In other localities, it is accompanied by, among others, enargite, luzonite, barite, beudantite, hinsdalite, and corkite. ## Localities The most important and confirmed kemmlitzite localities worldwide include: - Germany: Kemmlitz in Saxony (type locality). - USA: Goldfield in Nevada; Brewer Mine in South Carolina. - Japan: Teine mine in Hokkaido. - Argentina: Capillitas in Catamarca Province. - Italy: Baccu Locci mine in Sardinia.

Rarity

Very rare

For collectors

## Quality Criteria The quality of kemmlitzite specimens is primarily assessed based on the richness and aesthetics of microscopic aggregates. The most valued specimens are those with well-formed, rosette-like or radial clusters of small, shiny crystals, contrasting with the rock matrix. Due to the microscopic nature of the mineral, the size of individual crystals is not a key criterion; rather, the abundance and concentration of the mineral on the specimen's surface are important. ## Popular Localities Specimens from Goldfield, Nevada (USA) and the Teine mine (Japan) are prized by collectors specializing in "micromount" minerals due to their relatively well-developed crystalline aggregates.

Care and storage

## Cleaning Kemmlitzite specimens are extremely delicate due to the small size and softness of the crystals. Cleaning should be limited to an absolute minimum. If necessary, compressed air can be used to remove dust. Avoid contact with water and any chemical agents. ## What to Avoid Avoid ultrasonic cleaning, mechanical cleaning (e.g., with brushes), and exposure to chemicals, including acids and bases. The mineral is sensitive to shock and abrasion. Store away from heat sources. ## Storage It is recommended to store specimens exclusively in closed, padded "micromount" boxes to protect them from mechanical damage and dust. Display should be in stable conditions, away from vibrations and direct sunlight.

Sources

IMA Mineral List (CNMNC)