Manganoshadlunite
Chemical formula: (Fe,Cu)<sub>8</sub>(Mn,Pb)S<sub>8</sub>
Manganoshadlunite is a very rare iron, copper, manganese, and lead sulfide, found as microscopic grains in copper-nickel deposits.
Description
## Characteristics Manganoshadlunite is a sulfide belonging to the pentlandite group. It occurs as very small, irregular grains, rarely exceeding 0.5 mm, intergrown with other sulfides. It is an opaque mineral with a metallic luster and a brownish-yellow color, which, under a polarizing microscope in reflected light, shows a pinkish or brownish-pink hue. Due to its microscopic nature, it does not form specimens of ornamental value. ## Physical Properties The Mohs hardness of manganoshadlunite is approximately 4. This mineral is brittle and does not exhibit cleavage. Its density, calculated based on the chemical formula and unit cell parameters, is 4.61 g/cm³. It has a metallic luster. ## Colors and Varieties The mineral has a uniform, brownish-yellow color. No color or commercial varieties are distinguished. ## History and Name The name "manganoshadlunite" refers to the manganese dominant in its composition and its relation to shadlunite, of which it is a manganese analog. Shadlunite, in turn, was named after Tatiana Nikolaevna Shadlun (1912-1996), a Russian specialist in ore mineralogy. The mineral was officially recognized by the International Mineralogical Association (IMA) in 1979. ## Uses Manganoshadlunite has no industrial application. Its significance is purely scientific and as a collector's item, as a rare component of specific sulfide parageneses.
Diagnostic features
## Identification Identification of manganoshadlunite is impossible without specialized equipment. Due to the microscopic size of the grains, recognition requires the use of an ore microscope (for observation in reflected light) and chemical analysis (e.g., using an electron microprobe - EDS/WDS) to confirm the composition. The characteristic pinkish hue in reflected light is an indication but not a decisive feature. ## Distinguishing from Similar Minerals Manganoshadlunite is visually indistinguishable from shadlunite – chemical analysis is necessary to differentiate them, showing which element (manganese or lead) dominates at a given structural site. It can also be confused with other brown sulfides occurring in the same paragenesis, such as pentlandite, talnakhite, or cubanite. Only compositional analysis provides a definitive distinction. ## Crystal Forms This mineral forms exclusively anhedral (irregular, shapeless) grains and intergrowths within other minerals. No well-formed crystals have been observed.
Geological environment
## Genesis Manganoshadlunite is a hydrothermal mineral associated with copper and nickel sulfide deposits within differentiated mafic and ultramafic intrusions (gabbros and norites). It forms in the late stages of ore crystallization, often replacing earlier crystallized sulfides. ## Mineral Associations It most commonly co-occurs with other sulfides from the pentlandite and chalcopyrite groups. Typical associated minerals include shadlunite, talnakhite, mooihoekite, djerfisherite, pentlandite, cubanite, as well as galena and sphalerite. ## Localities The only confirmed and significant locality for manganoshadlunite worldwide is the copper-nickel deposits in the Norilsk region of Siberia, Russia, particularly the Oktyabrskoye and Talnakh deposits on the Putorana Plateau.
Rarity
Very rare
Collector aspects
## Quality Criteria The quality of manganoshadlunite specimens, being microminerals, is assessed based on the richness of the sample – i.e., the size and number of grains visible in the microscope's field of view. Specimens with analytically confirmed identity and those where manganoshadlunite co-occurs with other rare minerals from the same locality, forming interesting parageneses, are highly valued. ## Popular Localities The only source of collector specimens is the Cu-Ni deposits in the Norilsk region (Oktyabrskoye, Talnakh) in Russia. Specimens from this locality are the standard for this mineral.
Care and storage
## Cleaning Manganoshadlunite specimens are almost exclusively microminerals that do not require cleaning. If necessary, dusty samples can be cleaned with a soft brush or a stream of compressed air. Avoid contact with water and chemical agents. ## What to Avoid As a sulfide, the mineral may be susceptible to oxidation under high humidity conditions, which can lead to its slow decomposition. Avoid contact with acids and other aggressive chemicals. Store away from sources of moisture. ## Storage Specimens should be stored in a dry place, preferably in sealed "micromount" boxes that protect against dust and humidity fluctuations. A stable ambient temperature is also advisable.