Sewardite
A variety of Minerals
What is Sewardite?
Sewardite is a rare arsenate mineral with formula of CaFe2(AsO4)2(OH)2. Sewardite was discovered in 1982 and named for the mineralogist, Terry M. Seward (born 1940), a professor of geochemistry in Zürich, Switzerland.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Sewardite 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.
Sewardite Localities Map
See where Sewardite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Formation of Sewardite
Sewardite has only been found at three locations, in the Tsumeb mine in Tsumeb, Namibia, Mina Ojuela, Mapimi, Durango, Mexico, and La Mur, Las Animas mine, Sonora, Mexico. At the site in Durango, Mexico, it occurs as a dark, reddish spherules and rosettes of very thin, flaky crystals. This newly discovered mineral (confirmed as a species in 1998) has been determined as rare, since only 1–2 mg of it were found in the Tsumeb mine.
Quick Facts
Physical Properties
- Color
- Dark red to light orange
- Streak
- Reddish-brown
Chemical Properties
- Chemical Formula
- CaFe3+2(AsO4)2(OH)2
- Elements
- As, Ca, Fe, H, O
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Sewardite FAQs
How do I identify Sewardite?
Sewardite can be identified by its Dark red to light orange color. Look for these key characteristics when examining specimens.
What color is Sewardite?
Sewardite typically appears in Dark red to light orange. Color can vary depending on impurities and formation conditions.
What is the formation of sewardite of Sewardite?
Sewardite has only been found at three locations, in the Tsumeb mine in Tsumeb, Namibia, Mina Ojuela, Mapimi, Durango, Mexico, and La Mur, Las Animas mine, Sonora, Mexico. At the site in Durango, Mexico, it occurs as a dark, reddish spherules and rosettes of very thin, flaky crystals. This newly discovered mineral (confirmed as a species in 1998) has been determined as rare, since only 1–2 mg of it were found in the Tsumeb mine.
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