Gillardite
Chemical formula: Cu₃NiCl₂(OH)₆
Gillardite is a rare, dark green mineral of copper, nickel, chlorine, and hydroxyl, forming small crystals.
Description
## Characteristics Gillardite is a rare mineral that typically occurs as small, hexagonal crystals or aggregates. Its color is characteristically dark green, which aids in its preliminary identification. Crystals are often small but well-formed, making it interesting for collectors of rare minerals. ## Physical Properties Gillardite has a Mohs hardness of 3, meaning it is relatively soft. It has a green streak. It is transparent, and its cleavage occurs on the {101} plane. ## Colors and Varieties The only known color of gillardite is dark green. No significant varieties of this mineral are known. ## History and Name Gillardite was named after Peter Gillard, an Australian mineralogist and collector who discovered this mineral. Its description and recognition as a new mineral species took place in 1999. ## Uses Due to its rarity and small crystal size, gillardite has no industrial applications. It is exclusively a collector's mineral, valued by enthusiasts of rare species.
Diagnostic features
## Identification Gillardite can be identified by its characteristic dark green color, hexagonal crystal habit, and low hardness. The green streak is also an important diagnostic feature. ## Distinguishing from Similar Minerals Due to its rarity and specific chemical composition, gillardite is relatively easy to distinguish from other minerals. Visually similar copper minerals may have different hardness, streak, or crystallographic system. ## Crystal Forms Gillardite typically forms small, hexagonal crystals, often occurring in aggregates or as coatings on other minerals.
Geological environment
## Genesis Gillardite is a secondary mineral, formed in the oxidation zones of copper and nickel deposits. It forms as a result of hydrothermal processes, where solutions rich in copper, nickel, and chlorine react with surrounding rocks. ## Mineral Associations Gillardite often co-occurs with other secondary copper and nickel minerals, such as malachite, azurite, chrysocolla, and chlorine-bearing minerals. ## Localities The only known locality for gillardite is the Otter Shoot mine in Kambalda, Western Australia.
Rarity
Extremely Rare
Collector aspects
## Quality Criteria The most prized gillardite specimens are those with well-formed, distinct crystals of intense, dark green color. Larger crystal aggregates are also more desirable. ## Popular Localities Due to gillardite being known from only one locality, all specimens originate from the Otter Shoot mine in Kambalda, Western Australia.
Care and storage
## Cleaning Gentle cleaning of gillardite can be done with a soft brush and lukewarm water. Avoid strong rubbing to prevent damage to the delicate crystals. ## What to Avoid Avoid contact with acids and other aggressive chemicals that can destroy the mineral. Prolonged exposure to direct sunlight can also affect its color. It is also important to avoid sudden temperature changes. ## Storage Gillardite should be stored in a dry place, away from dust and direct light. It is best to place it in a closed display case or a box with soft lining to protect it from mechanical damage.