Ottoite is an extremely rare lead tellurite mineral discovered in the oxidized zones of tellurium-rich deposits in Mexico. It is typically found as small, pale yellow tabular crystals, often associated with other tellurium minerals like emmonsite.
Is this ottoite?
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 ottoite with a known reference. Ottoite 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: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, crystalline aggregates.
Often confused with
Ottoite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ottoite
Minerals reported to co-occur with ottoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂TeO₅
- Mohs hardness
- 3
- Density
- 8.721 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, crystalline aggregates
- Cleavage
- Two in the [100] zone at ~90°, possibly on {010} and {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary phase on fracture surfaces and in small vugs in quartz veins
Where rockhounds find ottoite
Classic worldwide localities
- Aga mine, and the Bird Nest Drift, Otto Mountain, ~2 km northwest of Baker, San Bernardino County, California, USA
Field-hunting tip
Where it forms: A secondary phase on fracture surfaces and in small vugs in quartz veins. If you start seeing acanthite, bromine-rich chlorargyrite, gold in float, you are in the right ground. Typical habit: tabular crystals, crystalline aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ottoite?+
Where is ottoite found?+
Is ottoite safe to handle?+
What rocks look like ottoite?+
What minerals are found with ottoite?+
What kind of rock does ottoite form in?+
What is ottoite used for?+
Find ottoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
