Vanpeltite

Chemical formula: (Mo⁶⁺₂O₅)(S⁴⁺O₃)·₄H₂O

Vanpeltite is an extremely rare, blue secondary molybdenum sulfite, discovered in the Freedom No. 2 mine in Utah, USA.

## Characteristics Vanpeltite is a hydrated molybdenum sulfite, occurring as very fine, bladed crystals not exceeding 40 micrometers in length and 2 micrometers in width. These crystals form rosette-like or spherical aggregates up to 0.1 mm in size. Due to the extremely small size of the crystals, its visual characteristics are difficult to observe without specialized equipment. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, luster, or fracture, have not been determined. The mineral is blue, and its streak is light blue. ## Colors and Varieties This mineral occurs in a uniform, blue color. No varieties have been distinguished. ## History and Name Vanpeltite was first described in 2024 by Anthony R. Kamp and his team. The mineral is named in honor of John "Jack" Van Pelt (b. 1957), an American mining geologist and director of the Mining Geology Museum at the Colorado School of Mines, for his contributions to the field of economic geology and mineral resources. ## Uses Vanpeltite has no practical applications. Its significance is purely scientific and as a collector's item, being an extremely rare and newly discovered mineral species.

Properties

Streak: Light blue
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of vanpeltite is possible only through advanced analytical methods, such as Raman spectroscopy and powder X-ray diffraction (PXRD), due to the microscopic size of the crystals. A preliminary diagnostic feature at the occurrence site may be its blue color and co-occurrence with other secondary molybdenum minerals. ## Distinguishing from Similar Minerals It can be confused with other blue, secondary minerals, such as chalcanthite, azurite, or linarite. Differentiation requires specialized laboratory tests. Vanpeltite is distinguished by its unique chemical composition (molybdenum sulfite). ## Crystal Forms It forms microscopic, bladed crystals that combine into spherical or rosette-like aggregates.

Geological environment

## Genesis Vanpeltite is a secondary mineral, forming in the oxidation zone of polymetallic deposits. It originated from the weathering of primary minerals, likely molybdenite, under low-temperature conditions. Its presence on mine dumps suggests that it is currently forming as a result of post-mining processes. ## Mineral Associations At the type locality, it co-occurs with gypsum, quartz, hematite, jarosite, molybdenite, pyrite, chalcopyrite, sphalerite, galena, and other rare secondary minerals such as powellite, hemimorphite, aurichalcite, and rosasite. ## Localities The only confirmed occurrence of vanpeltite worldwide is its type locality - the dumps of the Freedom No. 2 mine in the Marysvale mining district, Piute County, Utah, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the quality of a specimen is primarily determined by the richness and size of the aggregates on the rock matrix, as well as the intensity of the blue color. The most desirable specimens are those with well-formed, distinct spherical aggregates contrasting with the substrate. Association with other rare minerals is also important. ## Popular Localities The only source of specimens is the Freedom No. 2 mine in Utah, USA.

Care and storage

## Cleaning Due to the microscopic size and delicacy of the aggregates, mechanical cleaning is impossible and inadvisable. Specimens should be protected from dust. ## What to Avoid Contact with water, chemicals, ultrasound, and sudden temperature changes should be avoided. As a secondary mineral, it is likely unstable under variable environmental conditions. ## Storage Vanpeltite specimens should be stored exclusively in specialized "micromount" boxes, protecting them from mechanical damage, dust, and moisture. Exposure to direct light should be avoided.

External references

https://www.mindat.org/min-470926.html