mineral

Sulfur

Sulfur (S8)

Hardness: 1.5 - 2.5 on Mohs scale; Color: Bright yellow to greenish-yellow; Luster: Resinous to adamantine; Crystal Structure: Orthorhombic; Cleavage: Imperfect; Specific Gravity: 2.07

Hardness: 1
Color: Bright yellow to greenish-yellow
Luster: Resinous to adamantine

Identified May 21, 2026More mineral →

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Physical properties

Hardness: 1.5 - 2.5 on Mohs scale; Color: Bright yellow to greenish-yellow; Luster: Resinous to adamantine; Crystal Structure: Orthorhombic; Cleavage: Imperfect; Specific Gravity: 2.07

Formation & geological history

Commonly forms as a precipitate from volcanic gases (fumaroles/solfataras) or through the weathering of sulfide minerals. It also occurs in sedimentary evaporite deposits and salt domes via bacterial reduction of sulfate minerals.

Uses & applications

Primary source for sulfuric acid production. Used in the manufacture of fertilizers, gunpowder, matches, insecticides, rubber vulcanization, and various chemical processes. Also used in some traditional medicinal ointments.

Geological facts

Sulfur has been known since ancient times and is referred to as 'brimstone' in the Bible. It burns with a distinct blue flame and emits a suffocating odor of sulfur dioxide gas. Pure natural sulfur is actually odorless; the 'rotten egg' smell associated with it comes from hydrogen sulfide gas.

Field identification & locations

Identified in the field by its distinct yellow color, low hardness (can be scratched by a fingernail), and low melting point. It is very brittle. Common locations include Sicily (Italy), Indonesia (Kawah Ijen), and the Gulf Coast of the USA.