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 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ottoite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ottoite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, pale 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.
How to tell apart: Emmonsite is the harder of the two (Mohs 5 vs. 2-3); streak differs — Ottoite leaves white, Emmonsite leaves pale yellow; luster reads adamantine on Ottoite and vitreous on Emmonsite.
How to tell apart: Streak differs — Ottoite leaves white, Tlapallite leaves yellow; luster reads adamantine on Ottoite and resinous on Tlapallite.
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
- 2-3
- Density
- 6.08 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Crystalline Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Tellurium-bearing Ore Deposits
- Typical price
- $100-500 per specimen
Where rockhounds find ottoite
Classic worldwide localities
- Moctezuma, Sonora, Mexico
Field-hunting tip
Look in oxidized tellurium-bearing ore deposits country — that is the host setting where ottoite typically forms. If you start seeing emmonsite, tellurite, quetzalcoatlite in float, you are in the right ground. Field specimens usually show a tabular crystals, crystalline aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ottoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
