Orpiment
Orpiment
Published: June 2014
Modified: January 2022
Orpiment is an arsenic sulfide that grows in small masses with lemon-yellow to brownish-yellow coloring. Its name comes from a Latin term meaning "gold pigment," as this mineral was once used to make yellow paint. This gem is photosensitive and should not be exposed to light for prolonged periods.
General Information
Common Name
Orpiment
Species
Orpiment
Transparency
Transparent - Translucent
Dispersion
Strength: Extreme Fire
Refractive Index
Over The Limit 2.400-3.020
Birefringence
0.62
Optic Character
Biaxial
Optic Sign
Negative
Polariscope Reaction
Aggregate (AGG), Doubly Refractive (DR)
Fluorescence
SWUV: Inert
LWUV: Inert
LWUV: Inert
Pleochroism
Dichroic, strong yellow and greenish yellow
Hardness
1.5-2
Streak
Light Lemon Yellow
Specific Gravity
3.400-3.560 Typical:3.490
Toughness
Poor
Inclusions
Orpiment is usually found as a fibrous aggregate.
Luster
Pearly
Cleavage
Perfect, in one direction, Good, in one direction
Chemical Name
arsenic sulfide
Chemical Formula
As2S3
Crystal System
Monoclinic
Chemistry Classification
Sulfide
Orpiment Colors
-
Yellow
Alternate Names
Yellow Arsenic
Countries of Origin
Russian Federation; Unknown; United States of America
Care
Orpiment contains arsenic, wash hands after handling.