Pharmazincite

Chemical formula: KZn₂+As₅+O₄

Pharmazincite is a rare zinc potassium arsenate, forming colorless, tabular crystals with a vitreous luster.

## Characteristics Pharmazincite is a very rare mineral from the arsenate group, chemically classified as a zinc potassium arsenate. It occurs as small, colorless, tabular or bladed crystals, rarely exceeding 1 mm in length. The crystals are transparent and characterized by a vitreous luster. Due to its extreme rarity and small crystal size, it is a mineral known primarily in scientific circles and among specialized collectors. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of approximately 3. It is transparent, and its luster is described as vitreous. The density calculated based on the chemical formula and unit cell parameters is 4.21 g/cm³. ## History and Name The name "Pharmazincite" refers to its chemical composition and its resemblance to pharmacolite. The first part, "pharma-", comes from the mineral pharmacolite (calcium arsenate), to which it is related. The second part, "-zinc-", indicates the presence of zinc as the dominant cation. The mineral was approved by the International Mineralogical Association (IMA) in 2019 under number IMA2019-030. It was discovered in the dumps of the former silver and cobalt mine in Jáchymov, Czech Republic.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: White
Density: 4.21
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of pharmazincite in practice relies on advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD), due to its occurrence as microscopic crystals. Visually, it is a colorless, vitreous mineral forming small, tabular crystals on the host rock. ## Distinguishing from Similar Minerals It can be confused with other secondary arsenates, such as pharmacolite, annabergite, or erythrite, but it is distinguished by its colorless nature (unlike green annabergite and pink erythrite) and chemical composition. Final differentiation from other colorless arsenates requires chemical analysis to confirm the presence of potassium and zinc. ## Crystal Forms It forms thin, tabular or bladed crystals, often grouped into small aggregates or rosettes. The crystals are elongated and flattened.

Geological environment

## Genesis Pharmazincite is a secondary mineral, forming in the oxidation zones of ore deposits containing arsenic and zinc. It forms as a result of the weathering of primary arsenical minerals (e.g., skutterudite, arsenopyrite) and zinc minerals (sphalerite) in the presence of potassium-rich solutions. ## Mineral Associations At its type locality (Jáchymov), it co-occurs with other rare arsenates, such as svornostite, annabergite, erythrite, pharmacolite, gypsum, and with primary ores like skutterudite and uraninite. ## Localities The only confirmed occurrence of this mineral in the world is its type locality – old mine dumps in Jáchymov, in the Karlovy Vary region of the Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria As a mineral of primarily scientific and systematic importance, specimens where pharmazincite crystals are well-formed, clearly visible, and, most importantly, analytically confirmed, are most valued. The presence of interesting associated minerals that enrich the contextual value of the specimen is also crucial. ## Popular Localities The only source of specimens is Jáchymov in the Czech Republic. Material from this location is extremely rare and sought after by collectors specializing in systematic minerals and those from specific localities.

Care and storage

## Cleaning Due to its extreme rarity, small size, and potential fragility, mechanical cleaning is not recommended. If absolutely necessary, compressed air (from a safe distance) can be used to remove dust. Avoid contact with water and any chemicals. ## What to Avoid As an arsenate, this mineral is potentially toxic – avoid inhaling dust and wash hands after any contact. It should be protected from moisture, acids, cleaning agents, and high temperatures. Do not subject it to ultrasonic cleaning. ## Storage Pharmazincite specimens should be stored under stable conditions, in a closed, dry "micromount" container, away from sunlight and sources of moisture. Clear labeling of the mineral is necessary due to its arsenic content.

Sources

IMA Mineral List (CNMNC)