Kermesite

A variety of Minerals

Kermesite specimen

What is Kermesite?

Kermesite or antimony oxysulfide is also known as red antimony (Sb2S2O) . The mineral's color ranges from cherry red to a dark red to a black. Kermesite is the result of partial oxidation between stibnite (Sb2S3) and other antimony oxides such as valentinite (Sb2O3) or stibiconite (Sb3O6(OH)). Under certain conditions with oxygenated fluids the transformation of all sulfur to oxygen would occur but kermesite occurs when that transformation is halted.

Uses & Applications

Kermesite is named after a formerly used red dye, kermes (dye), and was so named because of the grainy reddish color the mineral often has. The name dates from 1832. Earlier in English (17th and 18th centuries) certain antimony compounds were called "kermes mineral" for the same reason. Kermesite or red antimony has been used as early as the Old Kingdom’s 6th Dynasty in ancient Egypt (c. 2345–2181 BCE) in lip cosmetics and in the 18th Dynasty Queen Hatshepsut (Maatkare) (1498–1483 BCE) negotiated with the Land of Punt for its colored antimony deposits. Besides stibnite, which was used for eye liner red, antimony is one of the oldest minerals used in cosmetics. Further archaeological evidence indicates that antimony levels were higher in ancient Egyptian female remains which had exposure to both antimony compounds (Bencze, 1994). Because of its color, the precipitate of kermesite was used as a coloring agent and in alchemy. Because of alchemy’s focus on material transformation as evidenced by color, red antimony was used to produce the red state. Kermesite is the mineral state for Kermes mineral which was used extensively in the medical field for centuries Presently, kermesite is collected for the beauty of its crystal metallic structure and not used in either cosmetics or the medical field any longer due to the toxic effects that it shares with antimony; less harmful substitutes have been found using both organic and pharmaceutical production.

Market Value Factors

Pricing varies for every rock and mineral, so use these universal factors to gauge Kermesite before comparing listings or appraisals.

Size & Weight

Larger, intact specimens usually command higher prices.

Rarity & Demand

Scarce material or popular varieties sell at a premium.

Condition & Finish

Chips, repairs, and heavy wear lower value; clean prep helps.

Treatment & Provenance

Untreated specimens with documented locality are prized.

Applies to all rocks & minerals.

Kermesite Localities Map

See where Kermesite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

Map preview
North ZoneCentral RidgeSouth Basin

Interactive map layers and collecting notes are available in the app.

More Images

Kermesite specimen
Robert M. Lavinsky

Quick Facts

Physical Properties

Color
Red
Hardness (Mohs)
1 - 1.5
Density
4.85 g/cm³
Streak
Brownish Red

Chemical Properties

Chemical Formula
Sb2S2O
Elements
O, S, Sb

Also Known As

KermesitePyrostibite
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Kermesite FAQs

How do I identify Kermesite?

Kermesite can be identified by its hardness of 1 - 1.5 on the Mohs scale, Red color. Look for these key characteristics when examining specimens.

What color is Kermesite?

Kermesite typically appears in Red. Color can vary depending on impurities and formation conditions.

How hard is Kermesite?

Kermesite has a hardness of 1 - 1.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.

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