Lazerckerite

Chemical formula: Ag₁+₃.₇₅Pb₂+₄.₅₀(Sb₃+₇.₇₅Bi₃+₄)S₂-₂₄

Lazerckeryt is a rare lead-silver mineral from the sulfosalt group, occurring as metallic, acicular crystals.

## Characteristics Lazerckeryt is a complex sulfosalt of silver, lead, antimony, and bismuth. It forms aggregates of fine, acicular or capillary crystals, which can reach up to 2 cm in length. Individual crystals are usually flexible. It occurs as aggregates or inclusions in other minerals, mainly in hydrothermal quartz veins. ## Physical Properties This mineral is characterized by a metallic luster and is opaque. Its Mohs hardness is 3-3.5, classifying it as a relatively soft mineral. The density is high, which is typical for lead-bearing minerals. ## Colors and Varieties Lazerckeryt ranges in color from steel-gray to black. The streak on a porcelain plate is black. No varieties have been distinguished. ## History and Name The mineral's name comes from its discovery locality – the historic mining area of Lazerz, near the village of St. Gertraudi in the Inn Valley in Tyrol (Austria). It was approved as a new mineral by the International Mineralogical Association (IMA) in 2019. It was described by a team of mineralogists led by Chris Stanley.

Properties

Mohs hardness: 3-3.5
Luster: Metallic
Streak: Black
Density: 6.16
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification A characteristic feature of lazerckeryt is the aggregation of very fine, flexible, acicular or capillary crystals with a metallic luster and steel-gray color. Its occurrence in association with other sulfosalts in quartz veins is also an important indicator. ## Distinguishing from Similar Minerals It can be confused with other acicular sulfosalts, such as jamesonite, boulangerite, or zinkenite. Reliable differentiation is almost exclusively possible using advanced analytical methods, such as chemical analysis (EDS) or X-ray diffraction (XRD), due to the presence of silver, lead, antimony, and bismuth in its composition. ## Crystal Forms It forms elongated, acicular or capillary crystals, often gathered in tangled aggregates. The crystals are flexible and can be slightly bent.

Geological environment

## Genesis Lazerckeryt forms as a result of hydrothermal processes in quartz veins that cut metamorphic rocks (phyllites). It crystallizes under low to medium temperature conditions from solutions rich in silver, lead, antimony, and bismuth. ## Mineral Associations This mineral co-occurs with quartz, galena, chalcopyrite, tetrahedrite, boulangerite, and other rarer bismuth and antimony sulfosalts. ## Localities The only confirmed occurrence of this mineral in the world is its type locality: the historic mining area of Lazerz, in the municipality of Reith im Alpbachtal, Tyrol, Austria.

Rarity

Very rare

For collectors

## Quality Criteria The most valuable lazerckeryt specimens are those that possess rich, dense aggregates of well-formed, undamaged, acicular crystals, clearly visible on a contrasting matrix, most often white quartz. The size of the crystals and the entire specimen also affects its attractiveness. ## Popular Localities As this mineral is known only from one locality in the world (Lazerz in Austria), all specimens available on the collector's market originate from there. This makes it extremely sought after by collectors specializing in rare minerals and type locality minerals.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the delicate nature of the acicular crystals, mechanical cleaning, including brushes, should be avoided. ## What to Avoid Avoid contact with water and chemicals, which can cause oxidation and damage to the mineral's surface. The crystals are very brittle and fragile, thus requiring careful handling. Do not heat the specimen. ## Storage It is recommended to store specimens in closed, stable containers (e.g., "membrane box" type) that protect delicate crystals from mechanical damage, dust, and humidity changes.

Sources

IMA Mineral List (CNMNC)