Zinczippeite

Chemical formula: Zn²⁺(U⁶⁺O₂)₂(S⁶⁺O₄)O₂·3.5H₂O

Zinczippeite is a rare, secondary uranium mineral from the zippeite group, forming characteristic yellow to orange coatings and aggregates.

## Characteristics Zinczippeite is a hydrated zinc uranyl sulfate, belonging to the zippeite group. It occurs as tiny, platy or acicular crystals, which most often form rosetted aggregates, spherulitic clusters, as well as earthy or powdery coatings and crusts on host rocks. Due to the very small size of the crystals, its features are usually observed on a microscopic scale. ## Physical Properties This mineral is very soft, with a hardness of approximately 2 on the Mohs scale. It is translucent, and its luster is described as dull, earthy, or silky in the case of fine-grained aggregates. It is highly radioactive due to its high uranium content. ## Colors and Varieties Zinczippeite ranges in color from bright yellow, through orange-yellow, to reddish-brown. No commercial or colored varieties are distinguished. ## History and Name The mineral's name refers to its chemical composition – the presence of zinc – and its relation to zippeite, the main mineral in the group. It was described and recognized as a new mineral in 1976 based on material from the Hillside mine in Yavapai County, Arizona, USA. ## Uses Due to its rarity and small accumulations, zinczippeite has no industrial application. It is solely an object of interest for collectors specializing in uranium minerals and scientists.

Properties

Mohs hardness
2
Luster
Dull
Density
0
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Zinczippeite is identified by its characteristic yellow to orange color, typical forms of occurrence (coatings, rosetted aggregates), and strong radioactivity, measurable with a Geiger counter. It often also exhibits intense, yellow-green fluorescence under ultraviolet light (both shortwave and longwave). ## Distinguishing from Similar Minerals It can be confused with other minerals from the zippeite group (e.g., sodium zippeite, magnesium zippeite) and other yellow secondary uranium minerals, such as tyuyamunite or carnotite. Definitive differentiation requires advanced chemical analyses (EDS/WDS) to confirm the dominance of zinc in its composition. ## Crystal Forms It forms microscopic, platy or acicular crystals, rarely exceeding fractions of a millimeter. Most often, they occur as radial or rosetted aggregates, as well as thin coatings and earthy crusts on rocks.

Geological environment

## Genesis It is a secondary mineral, formed in the oxidation (weathering) zones of uranium deposits, especially in the presence of zinc minerals such as sphalerite. It forms as a result of sulfate-rich waters acting on primary uranium ores, such as uraninite. It occurs in fractures and on the surfaces of sedimentary rocks (sandstones) or in hydrothermal veins. ## Mineral Associations It co-occurs with other secondary uranium minerals, such as andersonite, gypsum, johannite, schröckingerite, uranopilite, as well as with other minerals from the zippeite group. ## Localities The most important and classic locality, from which the type material originates, is the Hillside mine in Arizona (USA). It is also known from other localities in Utah and Colorado in the USA, as well as from Jáchymov in the Czech Republic and several places in Germany (Saxony).

Rarity

Very rare

For collectors

## Quality Criteria The most valued by collectors are specimens with well-formed, macroscopic crystalline aggregates of intense, orange color. Contrast with the rock matrix and the abundance of clusters on the specimen's surface are also important. Due to the microscopic size of the crystals, specimens suitable for microscopic photography (so-called "micromounts") are also sought after. ## Popular Localities Specimens from the type locality – the Hillside mine in Arizona – are considered classic. High-quality microcrystals also come from some mines in Utah, USA.

Care and storage

## Cleaning Zinczippeite specimens should generally not be wet cleaned. Fine, fragile aggregates can be easily damaged. A soft brush or compressed air from a safe distance can be used to remove dust. ## What to Avoid Contact with water and chemicals should be strictly avoided. The mineral is very soft and brittle, susceptible to mechanical damage. As a uranium mineral, it is highly radioactive – direct skin contact, inhalation of dust, and storage in areas of permanent human presence should be avoided. ## Storage Specimens should be stored in sealed, lead-lined or glass containers, appropriately marked with a radioactivity symbol. They should be kept away from other radiation-sensitive minerals, in a dry place and away from light sources to prevent possible color changes.

External references

Sources

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