Sulfur (Sulphur)
Sulfur (also spelled Sulphur in some countries) is one of the 30 native elements. Native element minerals are those elements that occur in nature in uncombined form with a distinct mineral structure. A few of the other native elements are Antimony, Carbon (Diamond), Copper, Gold, Osmium, Platinum and Silver.
Sulfur and Diamond are the only native elements that are usually available as faceted gems. Faceted Diamonds are common but facted Sulfur gems are somewhat rare because Sulfur is difficult to cut due to its very low Moh’s hardness of 1.5 – 2.5 and its high heat sensitivity. Sulfur is very brittle because of its poor heat conductivity. A cool Sulfur gem can actually crack if it is held in a warm hand. Sulfur is a common mineral but faceted gems are fairly rare.
Sulfur also has a bad reputation for having a strong odor. The Sulfur itself does not have an odor. This odor only occurs when Sulfur is exposed to water, water vapor or even humidity in the air. When this occurs, hydrogen sulfide (H2S) gas is produced which produces the strong odor. It is a powerfull odor which smells like rotten eggs. However, if Sulfur mineral specimens and gems are kept dry they will not emit the odor.
The name Sulfur is historically a Latin word. The original Latin spelling was sulpur, the later Greek spelling was sulphur. The sulfur spelling appeared toward the end of the Classical period (about AD 600). Sulphur has been the standard spelling in Britain since the 19th century while Sulfur has been the spelling in the USA and Canada has used both spellings. However, the International Union of Pure and Applied Chemistry (IUPAC) adopted the sulfur spelling in 1990. The Nomenclature Committee of the Royal Society of Chemistry restored the sulfur spelling to Britain in 1992.
Sulfur is available from many sources worldwide although fine crystal specimens are somewhat rare. Notable occurances include Michigan and Ohio in the USA; Bolivia; Chile; Poland; and Sicily, Italy.
Sulfur distribution: in the USA, large deposits occur in salt domes, as in Louisiana, especially in the area of Lake Charles, Chalcasieu Parish, and in Texas near Freeport, Brazoria County. At Sulfur Mountain, in Yellowstone Park, Wyoming. In California, at the Sulfur Bank mercury mine, on Clear Creek, Lake County. Crystals from quarries at Maybee and Scofield, Monroe County, Michigan. On Sicily, at Cianciana, Agrigento, and Racalmuto, the source of exceptionally large and fine crystals; from many other places in Italy, notably at Solfatara di Pozzuoli, near Naples; at Perticara, near Rimini, Marche; and at Carrara, Tuscany. Large crystals from Spain, at Conil, near Cádiz, Cádiz Province. In Baja California, Mexico, at San Felipe. Numerous other localities are known, the occurrence often inconspicuous.
| Chemistry | |
| Chemical Formula: | S8 or S |
| Elemental Sulfur | |
| Molecular Weight: | 256.53 gm |
| Composition: | Sulfur | 100.00 % | S | ||
| 100.00 % |
| Crystallography: | Orthorhombic – Dipyramidal |
| Crystal Habit: | Crystals dipyramidal on {111}, thick tabular and disphenoidal, to 20 cm; also massive, reniform, and forming stalactites; as a powder. |
| Twinning: | On {101}, {011}, {1l0}, rare |
| Cleavage: | Imperfect on {001}, {110} and {111}. Parting on {111}. |
| Fracture: | Irregular/uneven, conchoidal. Also can be somewhat sectile. |
| Tenacity: | Rather brittle to somewhat sectile |
| Moh’s Hardness: | 1.5 – 2.5 |
| Density: | 2.07 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Thermal Behaviour: with a low melting point of 113 degrees C, Sulfur burns readily in air, with a low blue flame, and gives off choking fumes of Sulfur-dioxide – acrid odor (forms sulfurous and eventually sulfuric acid in air). |
| Color: | Sulfur-yellow to honey-yellow, yellowish brown, greenish, reddish or yellowish gray; may be black from included organic matter. |
| Transparency: | Transparent, translucent |
| Luster: | Resinous, greasy |
| Refractive Index: | 1.708 – 1.773 Biaxial ( + ) |
| Birefringence: | 0.287 |
| Dispersion: | Relatively weak; r < v |
| Pleochroism: | Visible to distinct |
