Tlalocite is a very rare copper-zinc tellurite mineral discovered in the Moctezuma mine. It typically appears as bright azure-blue acicular crystals or thin crusts, often associated with other rare tellurium species in oxidized ore zones.
Is this tlalocite?
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 tlalocite with a known reference. Tlalocite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: blue, capri blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: encrustations.
Often confused with
Tlalocite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Quetzalcoatlite is the harder of the two (Mohs 3 vs. 1); streak differs, so Tlalocite leaves very pale blue, Quetzalcoatlite leaves pale blue, almost white; luster reads vitreous on Tlalocite and pearly to dull on Quetzalcoatlite.
How to tell apart: Denningite is the harder of the two (Mohs 4 vs. 1); streak differs, so Tlalocite leaves very pale blue, Denningite leaves white; luster reads vitreous on Tlalocite and adamantine on Denningite.
Often found alongside tlalocite
Minerals reported to co-occur with tlalocite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₁₀Zn₆(TeO₃)(TeO₄)₂Cl(OH)₂₅·27H₂O
- Mohs hardness
- 1
- Density
- 4.55 g/cm³
- Colors
- BlueCapri blue
- Streak
- Very pale blue
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Encrustations
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare in partially oxidized portions of a tellurium-bearing polymetallic hydrothermal sulfide vein
Where rockhounds find tlalocite
Classic worldwide localities
- Oriental (Bambollita) mine, northeast of the Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico
Field-hunting tip
Where it forms: Very rare in partially oxidized portions of a tellurium-bearing polymetallic hydrothermal sulfide vein. If you start seeing tenorite, azurite, malachite 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 tlalocite?+
Where is tlalocite found?+
Is tlalocite safe to handle?+
What rocks look like tlalocite?+
What minerals are found with tlalocite?+
What kind of rock does tlalocite form in?+
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Find tlalocite on the map
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