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Sulfur

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Sulfur is the tenth most common element by mass in the universe, and the fifth most common on Earth. It (also spelled sulphur) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent, and nonmetallic. Under normal conditions, atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature. It occurs in the form of sulfides, sulfates, and elemental sulfur. The bright yellow or orangish color of this mineral makes the mineral easy to identify. Sulfur forms pyramidal or tabular crystals, encrustations, powdery coatings, and granular or massive aggregates. Crystalline sulfur may exhibit as many as 56 different habits. Most sulfur forms in volcanic fumaroles, but it can also result from the breakdown of sulfide ore deposits. Massive form found in thick beds in sedimentary rocks, particularly those associated with salt domes. Sulfur is a poor conductor of heat, which means that specimens are warm to the touch.

Name: derived from the Latin word sulpur, which was Hellenized to sulphur. The spelling sulfur appears toward the end of the Classical period. (The true Greek word for sulfur, θεῖον, is the source of the international chemical prefix thio-.)

Association: Aragonite, Celestine, Calcite, Stibnite, Gypsum, Baryte, Galena, Anglesite, Quartz, Stibiconite

Member of: Sulphur Group

Morphology: Over 50 forms have been noted, blocky dipyramidal ones most common, also tabular and sphenoidal; also found as powdery coatings, massive material, and in reniform and stalactic forms.

Cell Parameters: a = 10.468 Å, b = 12.870 Å, c = 24.49 Å

Chemical Properties

Chemical Classification Native
Chemical Composition S
Common Impurities Se,Te

Sulfur Physical Properties

Color Yellow, sulphur-yellow, brownish or greenish yellow, orange, white
Streak Colourless
Luster Resinous, Greasy
Cleavage Imperfect/Fair Imperfect on {001}, {110} and {111}.
Diaphaneity Transparent, Translucent
Mohs Hardness 1,5 – 2,5
Crystal System Orthorhombic
Tenacity Brittle
Density 2.07 g/cm3 (Measured)    2.076 g/cm3 (Calculated)
Fracture Irregular/Uneven, Conchoidal
Parting Parting on {111}

Sulfur Optical Properties

Type Anisotropic
Color / Pleochroism Visible
2V: Measured: 68° , Calculated: 70°
RI values: nα = 1.958 nβ = 2.038 nγ = 2.245
Twinning On {101}{011}{110} rare
Optic Sign Biaxial (+)
Birefringence δ = 0.287
Relief Very High
Dispersion: relatively weak r< v

Occurrence

Sulfur is widely distributed in nature. It is found in many minerals and ores, e.g., iron pyrites, galena, cinnabar, zinc blende, gypsum, barite, and epsom salts and in mineral springs and other waters. It is found uncombined in some volcanic regions and in large underground deposits in Sicily and in Texas and Louisiana. Its often occurs with coal, petroleum, and natural gas. It is found in meteorities, and deposits of it may be present near the lunar crater Aristarchus. The distinctive colors of Jupiter’s moon Io are believed to result from forms of molten, solid, and gaseous sulfur. It is a component of all living cells. The amino acids cysteine, methionine, homocysteine, and taurine contain sulfur as do some common enzymes; it is a component of most proteins. Some forms of bacteria use hydrogen sulfide (H 2S) in place of water in a rudimentary photosynthesislike process. It is absorbed by plants from soil as sulfate ions.

Uses Area

  • Elemental sulfur is used mainly as a precursor to other chemicals. Approximately 85% (1989) is converted to sulfuric acid (H2SO4):
  • Large quantities of sulfites are used to bleach paper and to preserve dried fruit. Many surfactants and detergents (e.g. sodium lauryl sulfate) are sulfate derivatives.
  • When silver-based photography was widespread, sodium and ammonium thiosulfate were widely used as “fixing agents”. Sulfur is a component of gunpowder (“black powder”).
  • It is increasingly used as a component of fertilizers. The most important form of sulfur for fertilizer is the mineral calcium sulfate.
  •  It improves the efficiency of other essential plant nutrients, particularly nitrogen and phosphorus.
  • Organosulfur compounds are used in pharmaceuticals, dyestuffs, and agrochemicals. Many drugs contain sulfur; early examples being antibacterial sulfonamides, known as sulfa drugs. It is a part of many bacterial defense molecules.
  • Elemental sulfur is one of the oldest fungicides and pesticides. “Dusting sulfur”, elemental sulfur in powdered form, is a common fungicide for grapes, strawberry, many vegetables and several other crops.
  • Small amounts of sulfur dioxide gas addition (or equivalent potassium metabisulfite addition) to fermented wine to produce traces of sulfurous acid (produced when SO2 reacts with water) and its sulfite salts in the mixture, has been called “the most powerful tool in winemaking”.
  • It (specifically octasulfur, S8) is used in pharmaceutical skin preparations for the treatment of acne and other conditions. It acts as a keratolytic agent and also kills bacteria, fungi, scabies mites, and other parasites.
  • It can be used to create decorative inlays in wooden furniture. After a design has been cut into the wood, molten sulfur is poured in and then scraped away so it is flush.

References

  • Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
  • Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
  • Mindat.org. (2019). Orpiment: Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].
  • Smith.edu. (2019). Geosciences | Smith College. [online] Available at: https://www.smith.edu/academics/geosciences [Accessed 15 Mar. 2019].
Cite this article as: Mahmut Mat, "Sulfur", in Geology Science, [online] Accessed 21st August 2019, Available at: http://geologyscience.com/minerals/sulfur/
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