Malachite is a copper carbonate hydroxide mineral [Cu₂CO₃(OH)₂] renowned for its vibrant green coloration and distinctive banded patterns. As a secondary copper mineral, malachite forms through the oxidation and weathering of primary copper sulfide deposits in the near-surface environment.
Geologically, malachite develops in the oxidized zones of copper deposits where carbonate-rich groundwater interacts with copper-bearing minerals. The characteristic concentric banding results from rhythmic precipitation as fluctuating water tables and varying chemical conditions create alternating layers of dense and porous material over time.
The mineral crystallizes in the monoclinic system but rarely forms distinct crystals, instead occurring as botryoidal masses, stalactitic formations, or fibrous aggregates. Its intense green color derives from the copper content, specifically Cu²⁺ ions in the crystal structure. Malachite has a hardness of 3.5-4 on the Mohs scale and a density of approximately 4.0 g/cm³.
Formation typically occurs at temperatures below 200°C in near-surface environments where copper-bearing solutions encounter carbonate-rich host rocks or atmospheric CO₂. The banding patterns reflect episodic precipitation events, with each band representing specific geochemical conditions during formation.
Malachite commonly associates with azurite, chrysocolla, and cuprite in copper deposits worldwide.
