Dimorphite
| Dimorphite | |
|---|---|
| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) | 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 | |
| Formula 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 deposition in volcanic fumaroles at temperatures of 70–80 °C (158–176 °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 indicates the possibility of using synthetic dimorphite in the development of gas sensors,[5][6] due to the semiconductive properties of dimorphite.
References
- ↑ 1.0 1.1 Dimorphite mineral information and data Mindat.org
- ↑ 2.0 2.1 Handbook of Mineralogy
- ↑ Webmineral data
- ↑ 4.0 4.1 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.