Orpiment - As2S3

Orpiment, As2S3, is a common monoclinic arsenic sulfide mineral.
Orpiment is an orange to yellow mineral that is found worldwide, and occurs as a sublimation product in volcanic fumaroles, low temperature hydrothermal veins, hot springs and as a byproduct of the decay of another arsenic mineral, realgar. It is often found in association with realgar. It takes its name from the Latin auripigmentum (aurum = gold + pigmentum = pigment) because of its deep yellow color.

Optical properties:
• Cleavage: (010) Perfect • Color: Lemon yellow, Brownish yellow, Orange yellow.
• Habit: Foliated - Two dimensional platy forms; Massive - Fibrous - Distinctly fibrous fine-grained forms.

orpimentopozzuoli.jpg

volcanic fumaroles (Solfatara di Pozzuoli, phlegrean fields). The yellow-orange material is Orpiment.



orpiment(andy)(1).jpg

Panoramic view of orpiment thin section. Image by Andy Tindle (Virtual Microscope). PPL image, field of view = 2.5cm.




orpiment(andy)(2).jpg

Panoramic view of orpiment thin section. Image by Andy Tindle (Virtual Microscope). XPL image, field of view = 2.5cm.




Bibliography



• Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Optical Mineralogy : The Nonopaque Minerals by Phillips / Griffen
• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
• Nesse, William D., 1986, Introduction to Optical Mineralogy: New York, Oxford University Press

Photo
orpimento(2).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(3).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(4).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(5).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(6).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(7).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(8).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(9).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)
orpimento(10).jpg

Lamellar Orpiment crystals, Bagnore (Grosseto, Italy). PPL image, 2x (Field of view = 7mm)