Tugarinovite
Chemical formula: Mo<sup>4+</sup>O<sub>2</sub>
Molybdenum(IV) oxide, a very rare mineral with a characteristic brownish-violet color and metallic luster.
Description
## Characteristics Tugarinovite is a naturally occurring molybdenum(IV) oxide. It most often forms small, irregular grains and aggregates up to several millimeters in size. It is rarely observed in the form of prismatic crystals. Its most characteristic visual feature is its brownish-violet to dark brown color and strong, metallic or submetallic luster. It is an opaque mineral. ## Physical Properties The hardness of tugarinovite on the Mohs scale is approximately 3.5, classifying it as a relatively soft mineral. It has a high density, ranging from 6.44 to 6.57 g/cm³, which makes even small specimens heavy for their size. It does not exhibit cleavage, and its fracture is uneven. ## Colors and Varieties The dominant color is brownish-violet, which can transition to dark brown, and even black. The mineral does not form color varieties or commercial varieties. ## History and Name The mineral was first described in 1980 by a group of Russian mineralogists (V. G. Kruglova, G. A. Sidorenko, A. A. Dubakina, E. G. Ryabeva, L. S. Solntseva, I. G. Zhil'tsova). Its name commemorates Ivan Alekseevich Tugarinov (1905–1966), a Russian geochemist specializing in the geochemistry of uranium and molybdenum. ## Applications Due to its extreme rarity, tugarinovite has no industrial application. It is solely an object of scientific interest and is valued by specialized collectors of rare minerals.
Diagnostic features
## Identification Helpful identification features include: brownish-violet color, metallic luster, high density, and specific occurrence environment (U-Mo deposits). It often forms pseudomorphs after hexagonal molybdenite crystals, which is an important diagnostic clue. ## Distinguishing from Similar Minerals Tugarinovite can be confused with other dark, metallic minerals. It differs from the much more common molybdenite by its lack of cleavage, greater hardness, and different color (molybdenite is lead-gray). From uraninite, with which it often co-occurs, it differs by its lack of radioactivity and subtly different color. Certain differentiation from other rare oxides often requires chemical analysis (EDS). ## Crystal Forms It most often occurs as anhedral (unformed) grains and massive aggregates. It rarely forms small, columnar or prismatic crystals. Characteristic are aggregates of grains forming pseudomorphs after hexagonal molybdenite crystals.
Geological environment
## Genesis Tugarinovite is a hydrothermal mineral. It forms under reducing conditions in molybdenum-uranium deposits. It often forms as a result of alteration of previously formed molybdenite. ## Mineral Associations This mineral co-occurs with other U-Mo deposit minerals, such as molybdenite, uraninite, brannerite, as well as fluorite, calcite, quartz, and wulfenite. ## Localities The most important and classic localities for this mineral are in Russia. These include the Lenskoye deposit within the Streltsovka caldera (Zabaykalsky Krai) and the Kirovsk Mine in the Khibiny Massif on the Kola Peninsula. Occurrences in other parts of the world are few and of no collector significance.
Rarity
Extremely rare
Collector aspects
## Quality Criteria As an extremely rare mineral, every analytically confirmed specimen is valuable. Samples with visible, rich aggregates of tugarinovite are most highly prized, especially those forming pseudomorphs after molybdenite. Co-occurrence with other well-formed minerals, e.g., fluorite, also enhances attractiveness. ## Popular Localities The vast majority of collector material comes from the Lenskoye deposit in the Streltsovka caldera in Russia. Specimens from this locality are considered the best for this mineral.
Care and storage
## Cleaning Tugarinovite specimens should be cleaned very carefully, using a soft brush to remove dust. Distilled water may be used, but prolonged soaking should be avoided. Due to the small size of the grains, mechanical cleaning is risky. ## What to Avoid Ultrasonic cleaners and all chemical agents, especially strong acids, should be strictly avoided. The mineral is stable under normal conditions, so it does not require special protection from light or temperature. ## Storage It is recommended to store specimens in closed display boxes to protect them from dust and mechanical damage. As a stable mineral, it poses no threat to other specimens in the collection.