Simplotite
Chemical formula: CaV<sup>4+</sup><sub>4</sub>O<sub>9</sub>·5H<sub>2</sub>O
Simplotite is a rare, secondary vanadium mineral, forming aggregates of small, bladed crystals with an intensely green color.
Properties
- Mohs hardness
- 2.5
- Luster
- Vitreous
- Streak
- Greenish yellow
- Density
- 2.64
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Simplotite can be identified by its characteristic occurrence as small, acicular or bladed crystals forming rosetted or radial aggregates. Key features include its intensely green color, vitreous luster, and occurrence in the oxidation zones of uranium-vanadium deposits. ## Distinguishing from Similar Minerals - **Vésigniéite:** Has a similar green color but is harder and crystallizes in a different system. It usually forms more massive aggregates. - **Volborthite:** Often co-occurs with simplotite. It has a similar color but forms platy crystals, often in characteristic rosettes. It is a mineral of similar hardness. - **Malachite:** Has a similar green color but is a carbonate mineral and reacts vigorously with acids. It usually forms botryoidal, reniform, or fibrous habits with a different structure. ## Crystal Forms Simplotite forms elongated, bladed or acicular crystals, which almost always occur as aggregates. Most commonly, these are radial or rosetted aggregates, as well as spherulitic aggregates and thin coatings on host rocks.
Geological environment
## Genesis Simplotite is a secondary mineral, forming in the oxidation zones of uranium-vanadium deposits, which occur in sedimentary rocks, mainly sandstones. It forms under low-temperature conditions as a result of weathering and alteration of primary vanadium minerals, such as montroseite. ## Mineral Associations This mineral often co-occurs with other secondary vanadium and uranium minerals. The most common associations include: volborthite, carnotite, tyuyamunite, metatyuyamunite, gypsum, montroseite, and iron and manganese oxides. ## Localities The most important and classic simplotite localities are in the USA, on the Colorado Plateau, particularly in mines in Montrose County (Colorado) and San Juan County (Utah). It is also known from several other localities in these states. Outside the USA, its occurrence has been reported in very small quantities in Germany (Thuringia) and the Czech Republic.
Rarity
Very rare
For collectors
## Quality Criteria The collector appeal of simplotite depends on several factors. Most prized are specimens with well-formed, distinct rosettes or radial aggregates of fine crystals. The intensity and purity of the green color also increase the specimen's value. Contrast with the rock matrix and the absence of damage to the delicate crystals are also important. Due to the microscopic size of the crystals, specimens are often evaluated under magnification. ## Popular Localities The best and most sought-after simplotite specimens come from its type locality - the Simplot mine in Colorado, USA, and from other historic mines on the Colorado Plateau. Specimens from these locations are considered classic and serve as a benchmark for this mineral.
Care and storage
## Cleaning Simplotite specimens are extremely delicate and sensitive. Cleaning should be kept to an absolute minimum. If necessary, a very soft brush can be used to remove loose dust particles. Avoid all contact with water and other liquids. ## What to Avoid - **Water and moisture:** The mineral is soluble in water and acids; contact with them will cause its destruction. - **Vibrations and impacts:** Brittle and tiny crystals are susceptible to mechanical damage. - **High temperature and light:** Prolonged exposure to intense light or heat can lead to dehydration and color change. ## Storage Simplotite should be stored in a dry place, preferably in a tightly sealed collector's box (a "micromount box"), which protects it from dust, moisture, and mechanical damage. Display should be under controlled, low-humidity conditions.