Nagyágite is a rare and distinct lead-gold telluride mineral prized by collectors for its unique foliated or leaf-like crystal habit. It is most famous for its occurrence in the hydrothermal vein systems of Romania, where it often appears as flexible, metallic-lustered plates that can be mistaken for molybdenite. Collectors should handle it with care due to its heavy metal content and avoid creating dust during specimen cleaning.
Is this nagyágite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch nagyágite with a known reference. Nagyágite sits at Mohs 1-1.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Nagyágite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Nagyágite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: black, lead-gray.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, foliated masses, lamellar, massive.
Often confused with
Nagyágite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Nagyágite leaves black, Molybdenite leaves greenish-gray.
How to tell apart: Altaite is the harder of the two (Mohs 2.5-3 vs. 1-1.5).
How to tell apart: Streak differs — Nagyágite leaves black, Sylvanite leaves gray.
Often found alongside nagyágite
Minerals reported to co-occur with nagyágite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₅Au(Te,Sb)₄S₅-₈
- Mohs hardness
- 1-1.5
- Density
- 7.5 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Tabular Crystals, Foliated Masses, Lamellar, Massive
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Epithermal Gold-telluride Veins
- Typical price
- $50-500 depending on specimen size and clarity of crystal form
Where rockhounds find nagyágite
Classic worldwide localities
- Săcărâmb, Romania
- Crișcior, Romania
- Boulder County, Colorado, USA
- Kalgoorlie, Australia
- Kawazu mine, Japan
Field-hunting tip
Look in epithermal gold-telluride veins country — that is the host setting where nagyágite typically forms. If you start seeing sylvanite, petzite, gold in float, you are in the right ground. Field specimens usually show a tabular crystals, foliated masses, lamellar, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nagyágite on the map
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