Kambaldaite
Chemical formula: NaNi<sup>2+</sup><sub>4</sub>(CO<sub>3</sub>)<sub>3</sub>(OH)<sub>3</sub>·3H<sub>2</sub>O
A rare, hydrated sodium and nickel carbonate, forming characteristic acicular crystals of an intense green color.
Properties
- Mohs hardness
- 3
- Luster
- Vitreous
- Streak
- Pale green
- Density
- 3.13
- Cleavage
- Perfect on {1010}
- Fracture
- Uneven
- Transparency
- Translucent
- Crystal system
- Trigonal
Diagnostic features
## Identification Key diagnostic features of kambaldaite include its intense green color, its occurrence as radial or felt-like aggregates of acicular crystals, and its geological environment. Its reaction with acids is also characteristic – it dissolves rapidly, effervescing. ## Distinguishing from Similar Minerals Kambaldaite is sometimes confused with other secondary green nickel minerals, such as: - **Gaspéite-(Ce):** Usually has a lighter, yellowish-green color and forms earthy masses or crusts, less commonly acicular crystals. - **Annabergite:** Forms similar acicular aggregates but is an arsenate, not a carbonate. Differentiation often requires chemical analysis. - **Zaratite:** Occurs as vitreous, botryoidal crusts (mammillary habit), not acicular aggregates. ## Crystal Forms Kambaldaite crystallizes in the trigonal system, forming slender, hexagonal crystals with an acicular or capillary habit. These crystals almost always occur in radial, stellate, or tangled aggregates, as well as in the form of crusts on the host rock.
Geological environment
## Genesis Kambaldaite is a secondary mineral, formed in the oxidation (weathering) zones of nickel sulfide deposits. It forms as a result of the reaction of carbonate-rich waters with primary minerals, such as pentlandite, millerite, or violarite, in the presence of ultramafic rocks (e.g., komatiites). ## Mineral Associations It most often co-occurs with other secondary minerals of the oxidation zone, such as goethite, gypsum, magnesite, as well as with other rare nickel carbonates (e.g., gaspéite, hellyerite) and sulfates (morenosite). It often grows on relics of primary nickel sulfides. ## Localities The most important and well-known kambaldaite localities worldwide include: - **Australia:** Kambalda (Otter and Victor mines), Widgiemooltha in Western Australia – the source of the best specimens. - **Italy:** the area around Sestri Levante in Liguria. - **Greece:** in the Lavrion region. - **Germany:** Friedrichssegen mine in Rhineland-Palatinate.
Rarity
Rare
For collectors
## Quality Criteria The most prized kambaldaite specimens are characterized by an intense, emerald-green color and well-formed, radial aggregates of acicular crystals. Specimens where the green "hedgehogs" or "stars" of kambaldaite form an aesthetic contrast with the dark host rock (matrix) are highly valued. The size of the aggregates is also important, although large specimens are exceptionally rare. ## Popular Localities Specimens from the type locality – the Otter Shoot mine in Kambalda, Western Australia – are by far the most sought after by collectors. They are considered the global standard for this mineral.
Care and storage
## Cleaning Kambaldaite specimens are very delicate and sensitive. They should only be cleaned with compressed air to remove dust. Any contact with water, and especially with acids, is unacceptable, as the mineral is soluble in them. ## What to Avoid Absolutely avoid contact with water, chemical agents (including detergents), and acids. The mineral is sensitive to ultrasound and mechanical cleaning. It should be protected from high temperatures, which can lead to dehydration and destruction of its structure. ## Storage Specimens should be stored in closed, dry containers or display cases, away from sources of moisture and dust. Due to the fragility of its acicular crystals, it is best to place them in a "micromount" box to prevent mechanical damage.