Frohbergite is an uncommon iron telluride mineral typically found as microscopic inclusions within gold-telluride ores. Collectors usually seek it in polished sections or as distinct, metallic-gray aggregates associated with other telluride species in epithermal vein systems.
Is this frohbergite?
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 frohbergite with a known reference. Frohbergite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Frohbergite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Frohbergite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, pale rose, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: granular masses, microscopic inclusions.
Often confused with
Frohbergite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Marcasite is the harder of the two (Mohs 6-6.5 vs. 3.5); streak differs — Frohbergite leaves black, Marcasite leaves greyish-black.
How to tell apart: Löllingite is the harder of the two (Mohs 5.5-6 vs. 3.5); streak differs — Frohbergite leaves black, Löllingite leaves gray-black.
How to tell apart: Frohbergite is noticeably harder (Mohs 3.5 vs. 1.5-2); streak differs — Frohbergite leaves black, Sylvanite leaves gray.
Often found alongside frohbergite
Minerals reported to co-occur with frohbergite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeTe₂
- Mohs hardness
- 3.5
- Density
- 9.1-9.2 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Granular Masses, Microscopic Inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Epithermal Gold-telluride Deposits
- Typical price
- $50-300 for rare micro-specimens
Where rockhounds find frohbergite
Classic worldwide localities
- Kochbulak deposit, Uzbekistan
- Cripple Creek, USA
- Fornavs, Sweden
- Moctezuma, Mexico
Field-hunting tip
Look in epithermal gold-telluride deposits country — that is the host setting where frohbergite typically forms. If you start seeing gold, tellurium, rickardite in float, you are in the right ground. Field specimens usually show a granular masses, microscopic inclusions habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify frohbergite?+
Where is frohbergite found?+
How much is frohbergite worth?+
Is frohbergite safe to handle?+
What rocks look like frohbergite?+
What minerals are found with frohbergite?+
What kind of rock does frohbergite form in?+
What is frohbergite used for?+
Find frohbergite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
