Denningite is a rare tellurite mineral discovered in the Moctezuma Mine in Mexico. It typically forms thin, transparent, tabular crystals and is highly prized by collectors for its unique association with other rare tellurium minerals.

Hardness

Mohs

Luster

Adamantine

Streak

White

Transparency

Translucent to transparent

mineralrare

Denningite

Hardness: 4
Luster: Adamantine
Streak: White
Transparency: Translucent to transparent

Is this denningite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch denningite with a known reference. Denningite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: adamantine.
4
Match the color range
Compare against the expected color range: colorless, light green.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: tabular crystals.

Often confused with

Denningite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Quetzalcoatlite

Mohs 3

How to tell apart: Denningite is noticeably harder (Mohs 4 vs. 3); streak differs, so Denningite leaves white, Quetzalcoatlite leaves pale blue, almost white; luster reads adamantine on Denningite and pearly to dull on Quetzalcoatlite.

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Often found alongside denningite

Minerals reported to co-occur with denningite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CaMnTe₄O₁₀
Mohs hardness: 4
Density: 5.05 g/cm³
Colors: Colorless Light green
Streak: White
Luster: Adamantine
Transparency: Translucent to transparent
Crystal system: Tetragonal
Crystal habit: Tabular crystals
Cleavage: Perfect on {001}
Rarity: Rare
Uses: Collector
Host rock: In a hydrothermal Au–Te deposit

Where rockhounds find denningite

Classic worldwide localities

Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico

Field-hunting tip

Where it forms: In a hydrothermal Au–Te deposit. If you start seeing tellurium, tellurite, paratellurite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify denningite?+

Mohs hardness is 4. Luster: adamantine. The streak is white. Common colors include colorless, light green.

Where is denningite found?+

Notable localities include Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico.

Is denningite safe to handle?+

Contains tellurium; avoid inhaling dust or ingesting particles.

What rocks look like denningite?+

Denningite is most often confused with Quetzalcoatlite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with denningite?+

Denningite commonly co-occurs with Tellurium, Tellurite, Paratellurite, Spiroffite, Zemannite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does denningite form in?+

Where it forms: In a hydrothermal Au–Te deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is denningite used for?+

Denningite is used in collector.

Find denningite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.