The mineral sulfur

Chemical Formula

Composition

Sulfur

Color

Bright yellow to yellow-brown

Streak

White

Hardness

1½ - 2½

Crystal Forms
and Aggregates

(Orthorhombic) Steep bipyramidal and tabular crystals are common, sometimes occurring as hollow skeletons. Small grains, wheat sheaves, and encrustings occur. Massive, earthy specimens are prevalent, and may have bubbly holes throughout.

Transparency

Transparent to opaque

Specific Gravity

2.0 - 2.1

Luster

Adamantine on clean, clear crystal surfaces; otherwise resinous or dull

Cleavage

3,2

Fracture

Conchoidal

Tenacity

Brittle

Other ID Marks

1) Cracks when exposed to heat
2) Dissolves in warm water
3) May have a greasy feel
4) Gives off a mild, sulfuric odor. Odor becomes strong if heated

Other Names

Native Sulfur,

Sulphur,

Native Sulphur,

Brimstone

Polymorphs

Rosickyite or Rosickyite - Monoclinic form of sulfur

In Group

Native elements ; Nonmetallic elements

All About

Pure Sulfur is bright yellow. The color may be altered if impurities are present. Clay and selenium impurities, as well as volcanic mixtures in sulfur can cause it to be slightly red, green, brown, or gray. Sulfur often occurs in petroleum deposits, where it is found coated with greasy black petroleum.

Sulfur is soft, light in weight, and very brittle. Care must be exercised when handling and storing specimens. When kept moist or not allowed to dry when wet, hydrogen will mix with the Sulfur, forming hydrogen sulfide (H₂S), which causes the deterioration of a specimen. To prevent this, Sulfur should not be stored under humid conditions. It is best not to wash Sulfur specimens, as warm water can dissolve it. Sulfur also the tendency to crack when exposed to mild heat, including body heat. It should be handled as little as possible, and kept out of light to avoid cracking.

The earthy, massive, specimens usually come from volcanic sulfur springs, and have small, bubbly holes throughout. These specimens usually have a greasy feel, and exhibit a strong "rotten-egg" odor.

Much of the fine Sulfur crystals are destroyed by mining operations. Underground Sulfur deposits are flooded with hot water, causing the Sulfur to melt into a brine. The brine is pumped to the surface, where the water is evaporated and the sulfur recovered. Such mining operations destroy all specimens.

Sulfur crystallizes in the orthorhombic system, but an uncommon monoclinic form of sulfur also exists. This monoclinic form is scientifically considered a different mineral than Sulfur, and is scientific name is Rosickyite.

Uses

Sulfur is a common element, with many uses. Although most sulfur is extracted from sulfide minerals, Native Sulfur, being common, is also used as a source. The fine specimens from Agrigento and Cattolico in Sicily, Italy, are highly sought by mineral collectors.

Sulfur has many industrial uses. It is used in the manufacture of black powder, matches and explosives. It is also used to create rubber, in dyes, and as an insecticide and fungicide. It is also used in the manufacturing of sulfuric acid.

Striking Features

Color, softness, very low density, and habit of cracking when exposed to heat

Complex Tests

Melts at only 226° F (108° C) and gives off a blue flame with fumes that smell like rotten eggs

Popularity (1-4)

Prevalence (1-3)

Demand (1-3)

Distinguishing
Similar Minerals

Due to its unique properties, Sulfur is easily distinguishable from all minerals

Commonly
Occurs With

Barite, Celestine, Realgar, Cinnabar

Noteworthy
Localities

The most famous and classic specimens have come from the Italian mines on the island of Sicily, in the form of well crystallized and brightly colored gemmy crystals which are highly sought after. Specific Sicilian deposits include Agrigento (Girgenti), the Cozzodisi Mine (Casteltermini), Cianciana, and Cattolico. Another outstanding Italian locality is the Perticara Mine, Pesaro-Urbino Province, on the Italian mainland. Two other classic European localities are the Vodinskoye Deposit, Samarskaya, Russia; and the Machów mine, Tarnobrzeg, Poland.

Bolivia has recently been producing an unending source of fabulous specimens from the remote El Desierto mine in Potosí Department. Specimens include crystal plates on a crumbly matrix as well as some fairly large sized crystals.

A well-known Mexican occurrence is San Felipe, in Baja California Norte. In the U.S. fine Sulfur specimens have been found at Maybee, Monroe Co., Michigan; Steamboat Springs, Washoe Co., Nevada; and at Yellowstone National Park, Wyoming. The salt domes of Texas and Louisiana also contain vast Sulfur deposits , but the industrial mining methods destroys all crystals. A few drill cores from mining operations deep into the earth have in Texas and Louisiana have been found with fine Sulfur crystals on them, indicating that indeed excellent crystals within the earth are all but destroyed by the mining operations.

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Links

Picture Links

1. Crystal fragment of Sulfur
2. Small rounded Sulfur crystals
3. Glassy rounded Sulfur crystals on rock
4. Massive bubbly Sulfur