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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.

Orpiment Polished
Orpiment Classification
Common Name Orpiment
Species Orpiment
Orpiment Optical Properties
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
Pleochroism Dichroic, strong yellow and greenish yellow
Orpiment Characteristic Physical Properties
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
Orpiment Chemistry & Crystallography
Chemical Name arsenic sulfide
Chemical Formula As2S3
Crystal System Monoclinic
Chemistry Classification Sulfide

Orpiment Colors

  • Yellow Orpiment Yellow

Alternate Names

Yellow Arsenic

Countries of Origin

United States of America (the); Russian Federation (the)


Orpiment contains arsenic, wash hands after handling.

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Tim Matthews


Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.