- Dimorphite
-
Dimorphite General Category Sulfide mineral Chemical formula As4S3 Strunz classification 02.FA.10 Crystal symmetry Orthorhombic (2/m 2/m 2/m) - dipyramidal Unit cell a = 11.24 Å, b = 9.90 Å, c = 6.56 Å; Z = 4 Identification Molar mass 395.88 g/mol Color orange-yellow Crystal habit Groups of pyramidal crystals Crystal system orthorhombic Cleavage none Fracture brittle Mohs scale hardness 1.5 Luster adamantine Streak yellow Diaphaneity transparent Specific gravity 3.59 Optical properties Biaxial (+) Dispersion strong Ultraviolet fluorescence none Other characteristics burns without residue References [1][2][3] Dimorphite (chemical name tetraarsenic trisulfide) is a very rare orange-yellow chalcogenide mineral. In nature, dimorphite forms primarily by deposit in volcanic fumaroles at temperatures of 70°-80°C (158°F-176°F). Dimorphite was first discovered in a such a fumarole near Naples, Italy in 1849 by the mineralologist Arcangelo Scacchi (1810-1893). Since its discovery, dimorphite has been found in the Alacrán silver mine near Copiapó, Chile.[2] It has also been reported from Cerro de Pasco, Peru, and the Lavrion District Mines in Attica, Greece.[1]
Properties and applications
Dimorphite has two crystal forms, Α- and Β-. This property gives rise to its name, which comes from the Greek for "two" and "form." Dimorphite transitions between its α- and β- forms at around 130°C (266°F).[4]
Dimorphite can be synthesized by melting arsenic and sulfur together in the proper molar ratios in vacuum.[4]
Initial research done by professors from the Technical University of Moldova and the Bundeswehr University of Munich indicates the possibility of using dimorphite in the development of gas sensors,[5][6] due to the semiconductive properties of dimorphite.
References
- ^ a b Dimorphite mineral information and data Mindat.org
- ^ a b Handbook of Mineralogy
- ^ Webmineral data
- ^ a b Wiberg, Egon, Nils Wiberg, and Arnold Frederick Holleman. Inorganic Chemistry. San Diego: Academic Press, 2001.
- ^ Tsiulyanu, D.; Golbam, G.; Kolomeyho, E.; Melnic, O. (1996). "Photoconductivity and optical absorption of dimorphite thin films". Physica status soldi. B. 197 (1): 61–64. doi:10.1002/pssb.2221970110.
- ^ Marian, S.; Potje-Kamloth, K.; Tsiulyanu, D.; Liess, H. -D. (2000). "Dimorphite based gas sensitive thin films". Thin Solid Films 359 (1): 108–112. doi:10.1016/S0040-6090(99)00707-5.
Categories:- Arsenic minerals
- Sulfide minerals
- Orthorhombic minerals
Wikimedia Foundation. 2010.
