Name/Title
OrpimentEntry/Object ID
2004.1.18Description
Assemblage Zone: pegmatite dikes
Chemical Composition: As2S3
Crystal System: Hexagonal System
Description: Common Name: Orpiment
Chemistry: As2S3, Arsenic Sulfide
Group Name: Sulfides / Sulfosalts
Location: El Brusskiy Mine, Northern Caucasus region of Russia
Description: Thick white matrix base the orpiment crystal are the golden layer on top
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
Associated Minerals realgar, calcite, stibnite, barite and gypsum.
Other Characteristics: orpiment is unstable in light; specimens should be stored in complete darkness. Also usually has a distinct odor similar to sulfur, but is due to the arsenic.
Best Field Indicators are crystal habit, cleavage, odor and color
Fracture: Flaky
Hardness: 1 Talc
Luster: Pearly
Occurrence: 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.
Rock Type: Metamorphic
Specific Gravity: 3.4-3.5
Streak: Yellow
Texture: Crystalline
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
Suomynona Mineral Collection, Suomynona CollectionAcquisition
Accession
2004.1Source or Donor
Suomynona Mineral CollectionAcquisition Method
DonationDimensions
Width
5-3/4 inDepth
1-3/4 inLength
7-1/2 inWeight
2.79 ozDimension Notes
Dimension taken at widest pointsLocation
Location
Shelf
CS-D-2Room
Curation StorageBuilding
Crater Rock MuseumCategory
StorageMoved By
Curtis GardnerDate
January 3, 2024Location
Display Case
FS-12Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
May 25, 2023Notes
Added current locationLocation
Container
centerDrawer
top tierShelf
east sideCabinet
case #67Wall
centerHallway
Discovery HallBuilding
Crater Rock MuseumCategory
Permanent
