Sulfur Value, Price, and Jewelry Information

Triangle-cut sulfur, 1.60 cts, 8.6 mm, medium-dark, very slightly greenish yellow, Maybee, Monroe Co., Michigan. © The Gem Trader. Used with permission.

Sulfur (Sulphur)

Although sulfur is very abundant, facetable material is not. Sulfur is also enormously difficult to cut and almost impossible to wear, so faceted pieces have some scarcity value for collectors of unusual gems.

Sulfur (Sulphur) Information

Data Value
Name Sulfur (Sulphur)
Colors Yellow, yellowish brown, yellowish gray, reddish, greenish, orange, white.
Crystallography Orthorhombic. Crystals tabular and pyramidal, often well formed; massive; powdery.
Refractive Index 1.958-2.245
Luster Resinous to greasy.
Hardness 1.5-2.5
Wearability Display Only
Wearability Notes Display Only.
Fracture Conchoidal
Specific Gravity 2.05-2.09
Birefringence 0.291
Cleavage Imperfect
Dispersion 0.155
Heat Sensitivity Extremely sensitive.
Luminescence None.
Luminescence Present No
Transparency Transparent to translucent.
Absorption Spectrum Not diagnostic.
Formula

S + Se.

Pleochroism

Distinct in shades of yellow.

Optics

a = 1.958; β = 2.038; γ = 2.245. Biaxial (+),  2V= 68°.

Optic Sign Biaxial +
Etymology

Middle English sulphur, from the Latin sulpur, an ancient name for this mineral.

Occurrence

Sulfur is usually found in combination with metals as sulfides; it occurs in native form in volcanic and hot spring areas (deposited from vapor); sedimentary rocks, and in huge quantities at salt domes. Anaerobic bacteria acting on sulfate minerals can also produce native sulfur in salt domes.

sulfur crystals - Bolivia

A plate of gemmy, transparent sulfurs, 5.9 x 4.4 x 4.1 cm, El Desierto mine, San Pablo de Napa, Daniel Campos Province, Potosi Department, Bolivia. © Rob Lavinsky, www.iRocks.com. Used with permission.

Comments

The element sulfur or sulphur (S) occurs as a component of numerous gem species, including cinnabar and lapis lazuli. Sulfur itself can also form as a mineral as an orthorhombic crystal. Two sulfur monoclinic polymorphs, sulfur-β and rosickýite, will turn into the orthorhombic variety gradually at room temperature. The orthorhombic sulfur variety, also known as sulfur-α, occurs most commonly in nature.

Sulfur is famous for its many practical applications. However, it’s also famously ill-suited for faceting. Sulfurs are so heat sensitive that crystals held in hand may crack due to thermal shock. Since they have both “very brittle” and sectile tenacity, crystals dropped from a height of several inches would most likely chip or crack, and you could cut them with a knife. With a hardness of 1.5 to 2.5, they could also be scratched by a penny. And if you should get sulfur wet, even with perspiration or humidity, you’ll experience firsthand the Biblical brimstone’s famous odor of rotten eggs.

To put it mildly, sulfurs lack ideal jewelry stone properties. Furthermore, facetable material, as it were, is uncommon. Nevertheless, some enterprising lapidaries have met the challenge and successfully fashioned tiny gems. Collectors also prize well-formed, natural crystals for display as mineral specimens.

sulfur crystals - Sicily

“mellow smell-oh yellow,” beautiful sulfurs from Agrigento (Girgenti), Sicily, Italy. From the collection of the Canadian Museum of Nature, Ottawa, Canada. Photo by Mike Beauregard. Licensed under CC By 2.0.

Synthetics

Although natural sulfur is very abundant, as a mineral with applications in the production of items as diverse as medicine, gunpowder, fertilizer, wine, and rubber, it has also been synthesized in many forms for many research projects. Understandably, these synthetics don’t include facetable crystals for jewelry.

However, around 1975, an Italian ornithologist and natural history enthusiast created and sold synthetic crystals designed to appear as natural, top-quality Sicilian sulfurs. In 2000, Dr. Sergio Martinat brazenly admitted he created them. Evidently, he grew sulphur crystals on authentic matrix from Sicily, artfully arranged to resemble the appearance of highly prized natural Sicilian specimens. In fact, these synthetics proved difficult to distinguish from natural Sicilian sulfurs. In 2003, a team of geologists discovered an isotope analysis can determine if sulfurs supposedly from Sicily are likely from there. It turns out Dr. Martinat used non-Sicilian sulfur from salt domes for recrystallization.

sulfur crystal - Russia

A transparent, “architectural” sulfur crystal, 3.8 x 3.0 x 2.5 cm, Vodinskoye, Samara Oblast, Russia. © Rob Lavinsky, www.iRocks.com. Used with permission.

Sulfur with hydrocarbon inclusions - Cozzodisi Mine, Sicily

These bright Sicilian sulfurs have an unusually glassy luster as well as hydrocarbon inclusions. When forming on their calcite matrix, the crystals were exposed to oil and bitumen. As a result, they contain these materials inside. This also proves they are indeed natural Sicilian crystals, since these inclusions prove unique to this location. 18.0 x 13.0 x 12.0 cm, Cozzodisi Mine, Sicily, Italy. © Rob Lavinsky, www.iRocks.com. Used with permission.

Enhancements

No known gem treatments or enhancements.

Sources

Girgenti and Cianciana, Sicily have produced fine, large crystals coveted by collectors. However, these mines are now closed. Bolivia and Russia also produce fine crystals.

Other notable sources of display specimens include the following:

  • United States: California; Michigan; Nevada; Texas and Louisiana (salt domes); Wyoming.
  • Chile; Mexico; Namibia; Poland; Ukraine.
sulfur drill core - Texas

In some locations, such as Texas, sulfurs form in salt domes above oil deposits. When drilling for oil, drill cores may very rarely emerge with intact crystals, such as this specimen. Likely preserved as office decor for oil company executives, if you consider the cost of drilling, Rob Lavinsky quips, these make “the world’s most expensive paperweights.” 24.0 x 13.0 x 13.0 cm. Comanche Creek Mine, Pecos Co., Texas, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.

Stone Sizes

While transparent crystals exist that could yield stones over 50 carats, they make better display specimens than cutting material. Gem cutters may occasionally use broken crystals for faceting small gems.

Care

Jewelry use is simply not advisable. When storing or displaying sulfurs, make sure they’re dry and not exposed to direct sunlight, since heat and moisture will corrode them over time.

For more care recommendations, consult our gemstone jewelry care guide.

sulfur ornaments - Indonesia

Since sulfur melts so easily, artisans can cast it into complex shapes. Historically, woodworkers even used it to create inlays in furniture. These sulfur ornaments sold at Kawah Ijen Mountain in Indonesia were most likely cast as well. Ijen is home to a large sulfur mine and refinery. Photo by Okkisafire. Licensed under CC By-SA 3.0.