Maletoyvayamite

Chemical formula: Au₃Se₄Te₆

Maletoiwaiamite is an extremely rare gold seleno-telluride, forming microscopic, metallic grains in the oxidation zones of volcanic deposits.

## Characteristics Maletoiwaiamite is a very rare mineral from the sulfide group, classified as a gold seleno-telluride. It occurs as extremely small, anhedral (irregularly shaped) grains, reaching sizes up to 10-15 micrometers. It is observed as inclusions within other minerals, mainly nagyágite. Due to its microscopic size, its visual features are difficult to determine without specialized equipment. Under reflected light microscopy, it has a creamy-white color with a pinkish hue. ## Physical Properties Given the extreme rarity and microscopic size of the grains, most physical properties of maletoiwaiamite have not been determined. Hardness, density, cleavage, and fracture remain unknown. The luster is metallic, and the mineral is opaque. ## History and Name The mineral's name comes from its discovery locality – the Maletoyvayam deposit (Maletoiwajam) on the Kamchatka Peninsula in Russia. It was officially recognized by the International Mineralogical Association (IMA) in 2005 (IMA2005-035). It was described by N.D. Tolstykh and co-workers.

Properties

Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of maletoiwaiamite is only possible using advanced laboratory techniques, such as electron microprobe analysis (EMPA) to determine chemical composition and X-ray diffraction (XRD) for structural analysis. Under reflected light polarized microscopy, it is distinguished by its creamy-white color with a pinkish hue and weak pleochroism. ## Distinguishing from similar minerals Distinguishing it from other microscopic gold tellurides and selenides, such as kostovite (AuCuTe₄), krennerite (AuTe₂), or sylvanite ((Ag,Au)₂Te₄), requires precise chemical analysis. Visually, without specialized studies, it is impossible to distinguish. ## Crystal forms Maletoiwaiamite exclusively forms anhedral, irregular grains of microscopic size, usually as inclusions in other minerals.

Geological environment

## Genesis Maletoiwaiamite forms under low-temperature hydrothermal conditions, in the oxidation zones of gold and tellurium deposits associated with volcanic activity. It forms in an environment rich in selenium and tellurium. ## Mineral associations This mineral occurs in close association with other tellurides and selenides. It most commonly co-occurs with nagyágite, in which it forms inclusions. It is also accompanied by other gold, silver, and tellurium minerals, such as sylvanite, petzite, hessite, as well as pyrite and quartz. ## Localities The only confirmed locality (type locality) of maletoiwaiamite in the world is the Maletoyvayam gold deposit, located in the Sredinny Range on the Kamchatka Peninsula, in the Far Eastern Federal District of Russia.

Rarity

Extremely rare

For collectors

## Quality criteria Maletoiwaiamite does not appear on the collector's market as a standalone mineral. Its value is purely scientific, and it is an object of interest for specialized research institutions and museums. The only form in which it can be "possessed" is a fragment of host rock from the type locality, where the presence of the mineral has been analytically confirmed. The value of such a specimen is related to its rarity and scientific significance, rather than aesthetic qualities.

Care and storage

## Cleaning Due to its microscopic nature and occurrence as inclusions in other minerals, mechanical or chemical cleaning of individual maletoiwaiamite grains is practically impossible and unnecessary. The host specimen should be cleaned using methods appropriate for the dominant mineral (e.g., nagyágite). ## What to avoid Aggressive chemicals, ultrasound, and high temperatures should be avoided, as they could damage both the microscopic maletoiwaiamite inclusions and the surrounding minerals. The mineral is susceptible to oxidation. ## Storage Specimens containing maletoiwaiamite should be stored under stable conditions, in sealed containers protected from dust, moisture, and sudden temperature changes. It is best to store them in their original host rock.

Sources

IMA Mineral List (CNMNC)