Greenockite is the rare, vibrant mineral that serves as our primary source of cadmium.

Nature · Published 3 October 2026 Swipe more like this →

In short: This striking yellow-to-red crystal is the only mineral found in nature that holds significant amounts of cadmium. While it often appears as a thin coating on other ores, its discovery in 1840 revealed the source of a metal now essential for everything from rechargeable batteries to nuclear reactor control rods.

Greenockite, chemically identified as cadmium sulfide (CdS), crystallizes in the hexagonal system and is famously known for its vivid hues, ranging from honey yellow to deep red and brown. It was first identified in 1840 near Bishopton, Scotland, during the construction of a railway tunnel and was named in honor of Lord Greenock. Geologically, it typically forms as encrustations on sphalerite and other zinc-bearing minerals, often deposited by hydrothermal fluids.

Despite its status as the primary ore for cadmium, greenockite is rarely mined directly. Instead, most of the world's cadmium supply is recovered as a secondary by-product during the processing of zinc, lead, and copper ores. Because cadmium is present in small quantities—typically 0.1 to 0.3 percent—within zinc blende, smelters concentrate the metal by roasting the sulfide ore. The resulting fumes are then captured and refined to a purity exceeding 99.9 percent.

Cadmium itself is a soft, silver-white metal with a low melting point of 321 °C. Its industrial value is immense: it is used to electroplate steel and iron to prevent corrosion, particularly in marine environments, and serves as a critical component in nickel-cadmium batteries. However, the element is notoriously toxic, with poisoning resulting from the inhalation of its dust or vapor. This toxicity has largely curtailed its historical use as a pigment, though its stable, bright yellow form remains a high-grade option for specialized paints.

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