Name/Title
OrpimentEntry/Object ID
2009.62.214Description
Description: Common Name: Orpiment
Chemistry: As2S3, Arsenic Sulfide
Class: Sulfides and Sulfosalts
PHYSICAL CHARACTERISTICS:
Color is orange-yellow to yellow.
Luster is resinous to pearly
Transparency crystals are translucent to transparent.
Crystal System Monoclinic; 2/m
Crystal Habit: is usually foliated or earthy masses and crusts, also fiberous and as small tabular crystals that appear orthorhombic.
Cleavage is perfect in one direction producing flexible, non-elastic flakes.
Fracture is flaky.
Hardness is 1.5-2.
Specific Gravity is 3.5
Streak is yellow
Best Field Indicators are crystal habit, cleavage, odor and color.
Occurrence: Notable Occurances Romania; Peru; Japan; Mercur, Utah, USA and Australia.
Variety: Orpiment is a rare mineral that usually forms with realgar. In fact the two minerals are almost always together. Crystals of orpiment are extremely rare as it usually forms masses and crusts. The masses are sometimes transparent to a degree and have a gemmy quality to them. The yellow color is special to orpiment and can be confused only with a few other minerals. Orpiment is derived from the latin auripigmentum, or golden pigment. Its use as a dye or pigment is limited due to its instability. Over time, orpiment will deteriorate into a powder. The process takes a long time, but exposure to light will accelerate it. Specimens should be stored in dark, enclosed containers.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationLocation
Location
Display Case
FS-11Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Ian C.Date
January 29, 2025Notes
Installation/ locationLocation
Shelf
CS-I-1Room
Curation StorageBuilding
Crater Rock MuseumDate
February 3, 2024
