mineral

Zinc Ore (Sphalerite in Matrix)

Sphalerite (Zn,Fe)S within a carbonate or silicate host rock

Hardness: 3.5-4 (Mohs); Color: Dark brown to black (sub-metallic) interior with greyish-white host rock; Luster: Resin-like to sub-metallic; Crystal structure: Isometric; Cleavage: Perfect dodecahedral; Specific gravity: 3.9-4.2

Hardness: 3
Luster: Resin-like to sub-metallic

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes where hot, mineral-rich fluids circulate through fractures in limestone, dolostone, or other host rocks. These deposits can range from Precambrian to Tertiary in age depending on the location.

Uses & applications

Primary source of zinc metal for galvanizing steel, brass production, and batteries. Gem-quality specimens are faceted for collectors, though soft for jewelry use.

Geological facts

Sphalerite is known as 'blackjack' by miners due to its dark color. It often contains trace amounts of cadmium, gallium, or indium, making it a critical source of high-tech rare metals.

Field identification & locations

Identify in the field by its distinct sub-metallic sheen and sulfurous smell when scratched or struck with a hammer. Commonly found in MVT (Mississippi Valley-Type) deposits and near volcanic vents.

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