Montanite is an uncommon bismuth tellurate mineral typically formed as an alteration product in oxidized tellurium-bearing deposits. It is most frequently encountered as soft, yellow to white earthy crusts or powdery coatings associated with native tellurium and gold.
Is this montanite?
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 montanite with a known reference. Montanite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: dull to waxy.
- 4Match the color rangeCompare against the expected color range: greenish, greenish white, yellowish, white, light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: encrustations.
Often confused with
Montanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Montanite is noticeably harder (Mohs 3 vs. 2); luster reads dull to waxy on Montanite and subadamantine on Tellurite.
How to tell apart: Emmonsite is the harder of the two (Mohs ~5 vs. 3); streak differs, so Montanite leaves white, Emmonsite leaves pale yellow; luster reads dull to waxy on Montanite and vitreous on Emmonsite.
Often found alongside montanite
Minerals reported to co-occur with montanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi₂TeO₆·2H₂O
- Mohs hardness
- 3
- Density
- 3.7 g/cm³
- Streak
- White
- Luster
- Dull to waxy
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Encrustations
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An alteration product of tetradymite
Where rockhounds find montanite
Classic worldwide localities
- Highland, Silver Bow Co., and in German Gulch, Deer Lodge Co., Montana, USA
- Little Joe mine, Tombstone, Cochise Co., Arizona, USA
- Hatchita, Hidalgo Co., New Mexico, USA
- Nizhni Priamur’ya, otherwise not located, Russia
- Norongo, Captain’s Flat, New South Wales, Australia
- Nyirjes, near Gyöngyösslymos, Mátra Mountains, Hungary
Field-hunting tip
Where it forms: An alteration product of tetradymite. If you start seeing tetradymite, bismuthinite in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify montanite?+
Where is montanite found?+
Is montanite safe to handle?+
What rocks look like montanite?+
What minerals are found with montanite?+
What kind of rock does montanite form in?+
What is montanite used for?+
Find montanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
