|Crystal class||Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
|Unit cell||a = 11.24, b = 9.90
c = 6.56 [Å]; Z = 4
|Formula mass||395.88 g/mol|
|Crystal habit||Groups of pyramidal crystals|
|Mohs scale hardness||1.5|
|Optical properties||Biaxial (+)|
|Other characteristics||burns without residue|
Dimorphite, chemical name tetraarsenic trisulfide (As4S3), is a very rare orange-yellow arsenic sulfide mineral. In nature, dimorphite forms primarily by deposition in volcanic fumaroles at temperatures of 70–80 °C (158–176 °F). Dimorphite was first discovered in 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. It has also been reported from Cerro de Pasco, Peru, and the Lavrion District Mines in Attica, Greece.
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).
Dimorphite can be synthesized by melting arsenic and sulfur together in the proper molar ratios in vacuum.
- Dimorphite mineral information and data Mindat.org
- Handbook of Mineralogy
- Webmineral data
- 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 Solidi (b). 197 (1): 61–64. Bibcode:1996PSSBR.197...61T. 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. Bibcode:2000TSF...359..108M. doi:10.1016/S0040-6090(99)00707-5.