Novodneprite

Chemical formula: AuPb<sub>₃</sub>

Novodneprite is a rare gold-lead alloy, forming microscopic, metallic inclusions in other minerals.

## Characteristics Novodneprite is a natural alloy (amalgam) of gold and lead. It occurs as microscopic grains and inclusions, usually of irregular, less commonly rounded or elongated shape. Its size typically does not exceed 0.25 mm. It is observed in polished sections under a microscope, where it forms inclusions within crystals of beudantite and segnitite. Due to its nature, it does not form macroscopic crystals or specimens. ## Physical Properties As an opaque mineral with a metallic luster, novodneprite is characterized by high density, resulting from its high gold and lead content. Its hardness is low, which is typical for metals and their alloys. In reflected light, its color is grayish-white with a yellowish tint. ## History and Name The mineral was first described in 1999 by E.M. Spiridonov, T.N. Chvileva, N.F. Sokolova, V.V. Mamin, and A.E. Gekin. Its name comes from the discovery locality – the Novodneprovskoye deposit in northern Kazakhstan.

Properties

Mohs hardness: 2.5
Luster: Metallic
Density: 14.37
Cleavage: None
Transparency: Opaque
Crystal system: Cubic

Diagnostic features

## Identification Identification of novodneprite is possible only through advanced laboratory techniques. It requires analysis in reflected light (ore microscopy) and confirmation of chemical composition by methods such as X-ray microanalysis (EDS/WDS). Its characteristic grayish-white color with a yellowish tint in reflected light and its co-occurrence with gold and lead minerals are key indicators. ## Distinguishing from Similar Minerals It can be confused with other natural gold-lead alloys, such as anyuiite (AuPb₂) or hajhongite (Au₃Pb). Differentiation relies solely on precise analysis of the gold-to-lead ratio within the grain. Visually, it is indistinguishable from these minerals. ## Crystal Forms Novodneprite forms exclusively anhedral (irregular), microscopic grains and aggregates, often with irregular or rounded outlines. No well-formed crystals are known.

Geological environment

## Genesis Novodneprite forms in the oxidation (weathering) zones of hydrothermal, polymetallic gold deposits. It forms as a result of secondary processes, likely under low-temperature conditions. At the type locality (Novodneprovskoye), it occurs in caverns within listwanite quartzites. ## Mineral Associations This mineral co-occurs with other, often rare, secondary minerals. Its most important associations include native gold, beudantite, segnitite, anglesite, bindheimite, stibiconite, as well as other gold-lead alloys like anyuiite. ## Localities The main and so far only confirmed occurrence of novodneprite is its type locality – the Novodneprovskoye deposit in the Akmola Region, Kazakhstan.

Rarity

Extremely rare

For collectors

## Quality Criteria Novodneprite is not a collector's mineral in the traditional sense, as it does not form crystals or aggregates visible to the naked eye. Its value is purely scientific. For research institutions and specialized systematic collections, polished sections in which the presence of novodneprite has been analytically confirmed, along with photographic documentation and chemical data, are valuable.

Care and storage

## Cleaning Due to its occurrence as microscopic inclusions in other minerals, novodneprite is not subject to separate cleaning. The entire host mineral specimen is cared for, typically by using compressed air to remove dust. ## What to Avoid Contact with chemicals, especially acids, should be avoided, as they can react with both novodneprite and the surrounding minerals. Specimens containing this mineral should be protected from mechanical damage and scratching. ## Storage Storage under stable room conditions, in closed boxes or display cases, is sufficient to protect specimens containing microscopic novodneprite inclusions.

Sources

IMA Mineral List (CNMNC)