Thermaerogenite is a rare copper-aluminum oxide belonging to the spinel group, typically formed in volcanic fumarole environments. It usually appears as small, dark octahedral crystals deposited from volcanic gases.
Is this thermaerogenite?
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 thermaerogenite with a known reference. Thermaerogenite sits at Mohs ~7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brown, yellow-brown, red-brown, brown-yellow, or brown-red.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral.
Often confused with
Thermaerogenite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside thermaerogenite
Minerals reported to co-occur with thermaerogenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuAl₂O₄
- Mohs hardness
- ~7
- Density
- 4.870 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Cubic
- Crystal habit
- Octahedral
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In cavities and overgrown on earlier oxide minerals, often epitaxially, as sublimates around a volcanic fumarole
Where rockhounds find thermaerogenite
Classic worldwide localities
- Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka Peninsula, Far-Eastern Region, Russia
Field-hunting tip
Where it forms: In cavities and overgrown on earlier oxide minerals, often epitaxially, as sublimates around a volcanic fumarole. If you start seeing tenorite, hematite, orthoclase in float, you are in the right ground. Typical habit: octahedral. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify thermaerogenite?+
Where is thermaerogenite found?+
Is thermaerogenite safe to handle?+
What rocks look like thermaerogenite?+
What minerals are found with thermaerogenite?+
What kind of rock does thermaerogenite form in?+
What is thermaerogenite used for?+
Find thermaerogenite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
