Nitscheite
Chemical formula: (N³⁻H₄)₂[(U⁶⁺O₂)₂(S⁶⁺O₄)₃(H₂O)₂]·3H₂O
Nitscheite is a rare, secondary uranyl mineral characterized by its intense yellow color and transparent, tabular crystals.
Properties
- Mohs hardness
- 2
- Luster
- Vitreous
- Streak
- Very pale yellow
- Density
- 3.30
- Cleavage
- On {010}
- Fracture
- Sub-Conchoidal
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Nitscheite can be identified by its intense yellow color, tabular form of small crystals, often forming radial aggregates. Key diagnostic features include its strong fluorescence under ultraviolet light (both shortwave and longwave) and radioactivity. It is very soft and easily damaged. ## Distinguishing from Similar Minerals It can be confused with other yellow secondary uranium minerals, such as meta-autunite, uranophane, or zippeite. Distinguishing it from these often requires advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD). Preliminary indications may include crystal habit and the specific shade of yellow. ## Crystal Forms Nitscheite crystals are tabular, flattened parallel to the {010} plane. They are typically less than a millimeter in size. Most often, they form radial or chaotically arranged clusters and aggregates on the host rock.
Geological environment
## Genesis Nitscheite is a secondary mineral. It forms as a result of the weathering (oxidation) of primary uranium ores, mainly uraninite, in the presence of sulfides (e.g., pyrite) in an ammonia-rich environment. It crystallizes from aqueous solutions in voids and fractures of sedimentary rocks, such as sandstones. ## Mineral Associations This mineral co-occurs with other secondary uranyl sulfates and phosphates. In its type locality, it was found in association with gypsum, meta-autunite, metazeunerite, johannite, and deliensite. ## Localities The only confirmed and described occurrence of nitscheite in the world is its type locality: the Green Lizard Mine in the Red Canyon District, San Juan County, Utah, USA.
Rarity
Very rare
For collectors
## Quality Criteria The most valuable nitscheite specimens are those with well-formed, distinct crystals forming aesthetic, radial aggregates. Contrast with the dark host rock enhances visual appeal. The size of crystals and entire clusters is a key factor, although even micromount specimens are prized due to the mineral's rarity. ## Popular Localities The only source of nitscheite specimens is the Green Lizard Mine in Utah, USA. All specimens available on the collector's market originate from this single locality.
Care and storage
## Cleaning Nitscheite specimens should not be wet cleaned. Dust can only be removed with a soft brush or compressed air used from a distance and with low force. As a radioactive mineral, it requires specialized handling – avoid inhaling dust and wash hands after any contact. ## What to Avoid Absolutely avoid contact with water and other liquids, which can dissolve or damage the delicate crystals. The mineral is sensitive to changes in humidity and temperature. It should not be heated or exposed to direct sunlight. ## Storage Nitscheite must be stored in dry conditions, preferably in a sealed, airtight container (e.g., a "membrane box") that protects it from mechanical damage and humidity changes. Due to its radioactivity, it should be stored away from areas of permanent human habitation, in an appropriately labeled container.