Meyrowitzite
Chemical formula: Ca(U<sup>6+</sup>O<sub>2</sub>)(CO<sub>3</sub>)<sub>2</sub>·5H<sub>2</sub>O
A hydrated calcium uranyl carbonate, forming pale yellow, platy crystals in the oxidation zones of uranium deposits.
Properties
- Mohs hardness
- 2
- Luster
- Vitreous, Pearly on cleavages
- Streak
- Pale yellow
- Density
- 2.93
- Cleavage
- Perfect on {001}
- Transparency
- Transparent to Translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Key diagnostic features include a pale yellow or yellowish-green color, a habit of thin, platy crystals, perfect cleavage, and intense, bluish-white fluorescence under ultraviolet light (both shortwave and longwave). Its occurrence in association with other secondary uranium minerals on a sandstone matrix is also an important clue. ## Distinguishing from Similar Minerals It can be confused with other secondary uranyl carbonates such as andersonite, liebigite, or bayleyite. Andersonite crystallizes in the trigonal system and often forms rhombohedral crystals. Liebigite and bayleyite crystallize in the monoclinic system. Definitive differentiation of these minerals requires advanced research methods (e.g., X-ray diffraction), although subtle differences in crystal habit, color shade, and fluorescence can be helpful in visual identification. ## Crystal Forms It usually forms aggregates of thin, bladed or platy crystals, which arrange themselves into coatings and crusts on the host rock.
Geological environment
## Genesis This is a secondary mineral, forming in the oxidation zone of uranium deposits in sandstones. It forms as a product of the weathering of primary uranium ores (mainly uraninite) under the influence of carbonate-rich groundwater. It often crystallizes as an efflorescence in post-mining environments. ## Mineral Associations It co-occurs with other secondary uranium minerals such as andersonite, liebigite, and bayleyite, as well as with gypsum and calcite. The primary source of uranium is usually uraninite. ## Localities The type locality is the Markey Mine in San Juan County, Utah, USA. It has also been identified in several other uranium mines on the Colorado Plateau in the USA and in Jáchymov, Czech Republic.
Rarity
Very rare
For collectors
## Quality Criteria The most valuable collector specimens consist of rich aggregates of well-formed, distinct crystals on a contrasting matrix. The intensity of the color, the size of the crystals, and the degree of coverage of the host rock determine its attractiveness. The value of a specimen is also enhanced by its co-occurrence with other rare uranium minerals. ## Popular Localities The most classic and prized specimens come from the type locality - the Markey Mine in Utah, USA.
Care and storage
## Cleaning Due to its significant softness and perfect cleavage, mechanical cleaning is highly inadvisable. Dust can only be removed with a gentle stream of air. Contact with water should be avoided, as it can lead to structural changes in this hydrated mineral. ## What to Avoid Meyrowitzite is a uranium mineral and is radioactive. Caution should be exercised when handling specimens, hands should be washed after contact, and dust inhalation should be avoided. It is brittle and soft, so it must be protected from impacts and abrasion. It should also be protected from high temperatures, which can cause dehydration. Many uranyl minerals are sensitive to sunlight. ## Storage Specimens should be stored in closed, sealed, and clearly labeled containers to limit radon emission and dust dispersion. It is recommended to keep it away from other minerals that could be damaged by radiation. The best solution is a dedicated display case or box for radioactive minerals.