Milotaite

Chemical formula: Pd³⁺(SbSe)³⁻

Milotaite is an extremely rare palladium selenoantimonide, identified based on single grains within ultramafic rocks.

## Characteristics Milotaite is a mineral from the sulfide group, specifically a palladium selenoantimonide. It was described based on microscopic, anhedral (lacking crystal faces) grains not exceeding 150 micrometers in size. It occurs in association with other platinum-group minerals within ultramafic rocks. Its color in reflected light is grayish-white, without visible pleochroism or internal reflections. ## Physical Properties Due to the microscopic size of its grains, most of milotaite's physical properties have not been determined. Hardness, density, cleavage, and fracture remain unknown. The luster is metallic. ## History and Name The mineral was approved by the International Mineralogical Association (IMA) in 2020 under number IMA2020-055. The name honors Prof. RNDr. Miroslav Mílota, CSc. (born 1959), a Czech geologist from Palacký University Olomouc, in recognition of his contribution to the geological research of the Jeseníky Massif, where the mineral was discovered. It was described by a team of researchers, including Karel Malec and Jiří Sejkora. ## Applications Milotaite has no industrial or commercial applications. Its significance is purely scientific and limited to systematic mineralogy.

Properties

Mohs hardness
4.5
Color
Silvery grey
Luster
Metallic
Streak
Grey
Density
0
Fracture
Irregular/Uneven
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Milotaite identification is possible only through advanced laboratory techniques, such as chemical composition analysis using an electron microprobe (EDS/WDS) and backscattered electron diffraction (EBSD) analysis to confirm the crystal structure. In reflected light, it is grayish-white and indistinguishable from many other platinum-group sulfides and selenides without specialized analysis. ## Distinguishing from Similar Minerals It can be confused with other microscopic platinum-group minerals, such as isomertieite, mertieite-II, stibiopalladinite, or sudburyite, with which it co-occurs. Differentiation relies solely on precise analysis of the palladium, antimony, and selenium ratios. ## Crystal Forms Only anhedral, irregular grains have been observed.

Geological environment

## Genesis Milotaite forms as a result of hydrothermal processes within serpentinized and metamorphosed ultramafic rocks (peridotites). Its crystallization is associated with the remobilization of platinum-group elements (PGE) under low-temperature conditions. ## Mineral Associations It co-occurs with chromite, serpentine-group minerals, and other PGE minerals such as sudburyite, stibiopalladinite, isomertieite, mertieite-II, geversite, sperrylite, irarsite, as well as pentlandite, chalcopyrite, gersdorffite, and native gold. ## Localities The only known occurrence worldwide (type locality) is an abandoned serpentinite quarry in Nová Voda, near Chrastice, within the Sobotín Massif, Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, milotaite is not an object of collector trade in the traditional sense. Only host rock samples with thoroughly studied and documented presence of milotaite grains from the type locality have scientific value. The attractiveness of such a specimen is purely scientific and depends on the richness of the mineral association and the quality of the analysis performed.

Care and storage

## Cleaning Due to its microscopic nature and extreme rarity, milotaite specimens (embedded in the host rock) should not be subjected to any mechanical or chemical cleaning attempts. ## What to Avoid Avoid contact with any chemicals, ultrasound, and abrasion of the rock surface in which milotaite grains are embedded. ## Storage Specimens should be stored under stable conditions, in specialized "micromount" boxes, protected from dust, moisture, and mechanical damage.

External references

Sources

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