Hakite-(Zn)
Chemical formula: Cu¹⁺₆(Cu¹⁺₄Zn²⁺₂)Sb³⁺₄Se²⁻₁₃
A rare copper, zinc, and antimony selenide from the tetrahedrite group, forming small, metallic-lustered grains.
Properties
- Mohs hardness
- 3.5-4
- Color
- black
- Luster
- Metallic
- Streak
- Black
- Density
- 6.081
- Cleavage
- None
- Fracture
- Conchoidal
- Transparency
- Opaque
- Crystal system
- Isometric
Diagnostic features
## Identification Identification of hakite-(Zn) under amateur conditions is practically impossible. It requires advanced analytical methods, such as chemical composition analysis (EDS/WDS) using an electron microscope and X-ray diffraction (XRD). In polished sections under a polarizing microscope in reflected light, it has a characteristic reddish-brown hue. ## Distinguishing from Similar Minerals It can be confused with other minerals from the tetrahedrite group, such as tetrahedrite, tennantite, freibergite, or even hakite-(Hg). Differentiation is only possible based on precise chemical analysis to determine the dominant elements. ## Crystal Forms It most often occurs as irregular, small grains embedded in other minerals. Small, poorly formed crystals with a tetrahedral habit are rarely observed.
Geological environment
## Genesis Hakite-(Zn) is a hydrothermal mineral. It forms in ore veins, usually in association with other selenides and sulfides. Its crystallization occurs under low to medium temperature conditions from solutions rich in selenium, copper, antimony, and zinc. ## Mineral Associations It most commonly co-occurs with minerals such as clausthalite, umangite, berzelianite, chalcopyrite, pyrite, uraninite, hematite, as well as other selenides and sulfosalts. It also occurs in association with calcite and dolomite as gangue minerals. ## Localities The most important and classic localities for this mineral are: - **Czech Republic:** Předbořice near Kovářov (type locality) and Bukov near Rožná. - **Germany:** Roter Bär Mine in St. Andreasberg, Harz Mountains. - **Argentina:** Sierra de Cacho, La Rioja Province.
Rarity
Very rare
For collectors
## Quality Criteria The quality of a hakite-(Zn) specimen is primarily determined by its mineralogical context, rather than aesthetic value. The most prized samples are those from a well-documented locality, where hakite-(Zn) is clearly visible (despite its small size) and occurs in association with other rare minerals. Confirmation of identification through chemical analysis significantly increases the specimen's value. ## Popular Localities Specimens from the type locality in the Czech Republic (Předbořice) and from the historic mine in St. Andreasberg, Germany, are most sought after by collectors specializing in mineral systematics.
Care and storage
## Cleaning Due to its brittleness and rarity, mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Avoid contact with acids and other chemicals that may react with selenides and sulfides. The mineral is sensitive to oxidation, so it should be protected from moisture and sudden temperature changes. ## Storage Hakite-(Zn) specimens should be stored under stable conditions, preferably in sealed, dry containers (e.g., "micromount" boxes) away from light and moisture, to prevent oxidation processes that can damage its surface.