Hakite-(Fe)

Chemical formula: Cu¹⁺₆(Cu¹⁺₄Fe²⁺₂)Sb³⁺₄Se²⁻₁₃

Hakite-(Fe) is a rare selenium mineral of copper, iron, and antimony, forming small, metallic-lustered grains in association with other selenides.

## Characteristics Hakite-(Fe) is a rare mineral from the sulfosalt group, being a selenide of copper, iron, and antimony. It occurs as very small, anhedral (irregularly shaped) grains, usually not exceeding 0.1 mm in size. It is most often observed as inclusions in other minerals, primarily umangite. Due to the small size of its crystals, its macroscopic features are difficult to observe without specialized equipment, such as a reflected light microscope. ## Physical Properties This mineral is characterized by a metallic luster. Its Mohs hardness is approximately 4.5. It is opaque. The density calculated based on the chemical formula and unit cell parameters is 6.20 g/cm³. ## Colors and Varieties In reflected light (under the microscope), hakite-(Fe) is gray with a pinkish tint. It does not exhibit internal reflections. No color or commercial varieties are distinguished. ## History and Name The name "hakite" honors the Czech mineralogist and geochemist, Jaroslav Hak (1931–1997) from the Institute of Ore Research in Kutná Hora, for his contributions to the study of selenides. The suffix "-(Fe)" was added according to nomenclature rules to indicate that iron is the dominant divalent element in this particular variety of the mineral. The mineral was described in 1972.

Properties

Mohs hardness
3.5-4
Color
black
Luster
Metallic
Streak
Black
Density
6.011
Cleavage
None
Fracture
Conchoidal
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Identification of hakite-(Fe) is almost exclusively possible using advanced laboratory techniques, such as reflected light microscopy and chemical analysis (e.g., electron microprobe - EDS/WDS). In reflected light, it is gray with a pinkish tint and shows no anisotropy. ## Distinguishing from Similar Minerals It can be confused with other selenides of similar appearance under the microscope, such as berzelianite, umangite, klockmannite, or other minerals from the tetrahedrite group. Definitive distinction requires chemical composition analysis, which allows for the identification of iron and antimony as key components. ## Crystal Forms It usually forms very fine, anhedral (irregularly shaped) grains and aggregates, often as inclusions in other minerals. Well-formed crystals have not been observed.

Geological environment

## Genesis Hakite-(Fe) forms under hydrothermal conditions, in ore veins rich in selenium. It forms at low to medium temperatures, crystallizing from solutions containing copper, iron, antimony, and selenium. ## Mineral Associations It most commonly co-occurs with umangite, berzelianite, klockmannite, eskebornite, tyrrellite, chalcopyrite, pyrite, hematite, goethite, calcite, and dolomite. ## Localities The most important and classic localities for this mineral are selenium deposits in the Czech Republic, especially Bukov and Předbořice near Klatovy. It has also been reported in the Tumiñico mine in Sierra de Cacho, Argentina, and in a uranium mine in the Athabasca Lake region, Saskatchewan, Canada.

Rarity

Very rare

For collectors

## Quality Criteria As a microscopic mineral, hakite-(Fe) is not evaluated according to typical criteria such as crystal size or form. The collector's value of a specimen lies in the richness of the mineral association and in the confirmation of the presence of hakite-(Fe) itself through analysis. The most valuable samples are those from the type locality (Czech Republic) with clearly visible microscopic aggregates in association with other rare selenides.

Care and storage

## Cleaning Due to the extreme rarity and small size of the grains, hakite-(Fe) specimens are practically not subject to cleaning under amateur conditions. Any interventions should be left to specialists in laboratories. ## What to Avoid Contact with chemicals, especially acids, which can react with selenides, should be avoided. Ultrasound and sudden temperature changes should also be avoided. As an opaque mineral, it is insensitive to light, but it should be protected from moisture and oxidation. ## Storage Specimens containing hakite-(Fe) should be stored under stable conditions, preferably in sealed, dry containers (e.g., systemic boxes), to minimize the risk of oxidation and chemical degradation. They should be protected from mechanical damage.

External references

Sources

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