mineral

Sulfur (Sulphur)

Sulfur (S8)

Color: Bright yellow to greenish-yellow. Hardness: 1.5 - 2.5 on the Mohs scale. Luster: Resin-like to greasy. Crystal System: Orthorhombic. Cleavage: Poor. Specific Gravity: ~2.07. Streak: White. Very soft and brittle, with a low melting point and a distinct odor when burned or rubbed.

Hardness: 1
Color: Bright yellow to greenish-yellow
Luster: Resin-like to greasy

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Sulfur forms near active volcanic fumaroles and hot springs as a sublime deposit from volcanic gases, or via anaerobic bacteria breaking down sulfate minerals in sedimentary evaporite beds.

Uses & applications

Used extensively in industrial chemistry to produce sulfuric acid, fertilizers, matches, gunpowder, rubber vulcanization, insecticides, and pharmaceuticals. Fine crystalline specimens are popular among collectors.

Geological facts

Native sulfur is often called 'brimstone' in historical texts. Burning sulfur produces a distinctive choking blue flame and fumes of sulfur dioxide. It has an extraordinarily low thermal conductivity, meaning touching a cool sulfur crystal can cause it to crack due to heat from a human hand.

Field identification & locations

Identified by its signature bright yellow color, soft feel, light weight, resinous luster, and faint odor. Commonly found near active volcanoes, volcanic deposits (e.g., Sicily, Italy; Indonesia; Iceland) and in salt domes (e.g., Gulf Coast of USA). Collectors should handle carefully as specimens are fragile and susceptible to thermal shock.