Semseyite
A variety of Plagionite Group
What is Semseyite?
Semseyite is a rare mineral with a grey-ish black appearance. This mineral was named after Andor von Semsey who was an amateur mineralogist in Hungary. Semseyite is a brittle mineral. It is present at high temperatures in hydrothermal conditions and is usually found near volcanic activity.
Etymology & Origins
Semseyite was first described for an occurrence in the Felsöbánya mine in Baia Sprie, Romania in 1881 by József Sándor Krenner (1839–1920). The mineral was named after Hungarian mineralogist Andor von Semsey (1833–1923).
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Semseyite 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.
Semseyite Localities Map
See where Semseyite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Formation of Semseyite
Semseyite forms in hydrothermal solutions at temperatures between 300 and 350 °C. It occurs in association with bournonite, jamesonite, sphalerite, zinkenite, sorbyite, guettardite, jordanite, diaphorite, galena, pyrite, chalcopyrite, tetrahedrite, arsenopyrite and siderite.
Health & Safety Information
- ⚠️Semseyite dust is toxic because it contains heavy metals Lead, Antimony.
- ⚠️Lead, Antimony
- ⚠️It's advisable to handle semseyite carefully to avoid generating dust and wash hands thoroughly afterward. When cutting or polishing semseyite, wear a dust mask to prevent inhaling heavy metal particles. Store semseyite in a sealed container in a well-ventilated area, away from children and pets. For those involved in crystal healing, never put it in your mouth.
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Quick Facts
Physical Properties
- Color
- Steel-grey to black
- Hardness (Mohs)
- 2.5
- Density
- 6.15 g/cm³
- Streak
- Black
- Luster
- Metallic
- Crystal System
- Monoclinic
Chemical Properties
- Chemical Formula
- Pb9Sb8S21
- Elements
- Pb, S, Sb
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Semseyite FAQs
How do I identify Semseyite?
Semseyite can be identified by its hardness of 2.5 on the Mohs scale, Steel-grey to black color, Metallic luster, Monoclinic crystal system. Look for these key characteristics when examining specimens.
What color is Semseyite?
Semseyite typically appears in Steel-grey to black. Color can vary depending on impurities and formation conditions.
How hard is Semseyite?
Semseyite has a hardness of 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the formation of semseyite of Semseyite?
Semseyite forms in hydrothermal solutions at temperatures between 300 and 350 °C. It occurs in association with bournonite, jamesonite, sphalerite, zinkenite, sorbyite, guettardite, jordanite, diaphorite, galena, pyrite, chalcopyrite, tetrahedrite, arsenopyrite and siderite.
