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Dimorphite

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(Redirected from Tetraarsenic trisulfide)
Dimorphite
General
CategorySulfide mineral
Formula
(repeating unit)
As4S3
IMA symbolDim
Strunz classification2.FA.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPnma
Unit cella = 11.24, b = 9.90
c = 6.56 ; Z = 4
Identification
Formula mass395.88 g/mol
Colororange-yellow
Crystal habitGroups of pyramidal crystals
Cleavagenone
Fracturebrittle
Mohs scale hardness1.5
Lusteradamantine
Streakyellow
Diaphaneitytransparent
Specific gravity3.59
Optical propertiesBiaxial (+)
Dispersionstrong
Ultraviolet fluorescencenone
Other characteristicsburns without residue
References

Dimorphite, chemical name arsenic sesquisulfide (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 mineralogist 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.

Initial research indicates the possibility of using synthetic dimorphite in the development of gas sensors, due to the semiconductive properties of dimorphite.

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Dimorphite mineral information and data Mindat.org
  3. ^ Handbook of Mineralogy
  4. Webmineral data
  5. Guarini G, Palmieri L, Scacchi A (1855) Chapter 5. Esame mineralogico-chimico delle produzioni dell'incendio, in Memoria sullo Incendio Vesuviano, Gaetano Nobile (Napoli) p. 165-200
  6. ^ Wiberg, Egon, Nils Wiberg, and Arnold Frederick Holleman. Inorganic Chemistry. San Diego: Academic Press, 2001.
  7. 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.
  8. 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.
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