Nukundamite
Chemical formula: Cu₃.₄Fe₀.₆S₄
Nukundamite is a rare copper iron sulfide, forming thin, hexagonal plates with a metallic luster and a characteristic reddish-purple color.
Properties
- Mohs hardness
- 3.5
- Color
- copper-red
- Luster
- Metallic
- Streak
- Black
- Density
- 0
- Cleavage
- (0001) perfect
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Trigonal
Diagnostic features
## Identification Key diagnostic features of nukundamite include its unique reddish-purple color, strong metallic luster, and characteristic form of thin, hexagonal plates. Its occurrence in association with other copper and zinc sulfides in a specific geological environment is also an important indicator. ## Distinguishing from Similar Minerals Nukundamite can be confused with covellite, which also has a bluish-purple color and metallic luster. However, covellite is usually more blue and less often forms such regular, hexagonal crystals. Final distinction often requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS). ## Crystal Forms Nukundamite crystallizes in the form of very thin, hexagonal plates. Crystals are typically small, with a diameter of less than 1 mm. They occur as single lamellae or small aggregates grown on other minerals.
Geological environment
## Genesis Nukundamite is a hydrothermal mineral. It forms as a result of the alteration (metamorphism) of volcanogenic massive sulfide (VMS) deposits. It develops in copper-enriched zones under relatively low-temperature conditions. ## Mineral Associations This mineral co-occurs with other sulfides. At its type locality in Fiji, it was found in association with sphalerite, pyrite, chalcopyrite, and covellite. In other localities, it is also accompanied by bornite and tennantite. ## Localities The most important and type locality is the Undu mine in the Nukundamu district on Viti Levu Island, Fiji. Its presence has also been confirmed at the Kidd Creek mine in Ontario (Canada) and in several locations in Japan, including the Furutobe and Ainai mines in Akita Prefecture.
Rarity
Very rare
For collectors
## Quality Criteria The collecting appeal of nukundamite primarily depends on the size and development of its crystals. Specimens with clearly visible, sharply defined, hexagonal plates of intense reddish-purple color are most valued. The contrast with the matrix mineral on which the crystals occur is also important. Due to the microscopic nature of most specimens, their photogenicity and the possibility of observation under magnification are crucial. ## Popular Localities By far the most classic and sought-after specimens come from the type locality in Fiji (Undu mine, Nukundamu). Specimens from Canada (Kidd Creek Mine) are also known, though rarer on the collector's market.
Care and storage
## Cleaning Nukundamite specimens are extremely delicate and usually occur as tiny inclusions or coatings. Mechanical or chemical cleaning is not recommended. If absolutely necessary, compressed air can be used to remove dust, but from a very safe distance and with utmost caution. ## What to Avoid Avoid contact with all chemicals, acids, and detergents. The mineral is susceptible to oxidation, so it should be protected from moisture and sudden temperature changes. It should not be washed with water or cleaned ultrasonically. ## Storage Nukundamite specimens should be stored in stable conditions, preferably in a sealed, airtight "micromount" box away from dust, moisture, and direct sunlight. Due to its softness and perfect cleavage, any physical contact with the crystal surface should be avoided.