Eurekadumpite is a rare secondary tellurium mineral typically found as deep blue-green to turquoise coatings or tiny crystalline crusts in oxidized ore zones. It is highly sought after by micromounters and collectors of rare tellurium species due to its scarcity and distinct, vibrant coloration.
Is this eurekadumpite?
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 eurekadumpite with a known reference. Eurekadumpite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light turquoise.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly flakes, silky aggregates.
- 4Match the color rangeCompare against the expected color range: deep blue-green, turquoise.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microcrystalline aggregates, crusts, powdery coatings.
Often confused with
Eurekadumpite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Eurekadumpite leaves light turquoise, Tellurite leaves white; luster reads pearly flakes, silky aggregates on Eurekadumpite and subadamantine on Tellurite.
How to tell apart: Emmonsite is the harder of the two (Mohs ~5 vs. 2.5-3); streak differs, so Eurekadumpite leaves light turquoise, Emmonsite leaves pale yellow; luster reads pearly flakes, silky aggregates on Eurekadumpite and vitreous on Emmonsite.
Often found alongside eurekadumpite
Minerals reported to co-occur with eurekadumpite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu,Zn)₁₆(TeO₃)₂(AsO₄)₃Cl(OH)₁₈·7H₂O
- Mohs hardness
- 2.5-3
- Density
- 3.76 g/cm³
- Colors
- Deep blue-greenTurquoise
- Streak
- Light turquoise
- Luster
- Pearly flakes, silky aggregates
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Microcrystalline aggregates, crusts, powdery coatings
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidation zone of quartz-sulfide ores containing tellurides (mostly hessite) in small cavities and in fractures in quartz
Where rockhounds find eurekadumpite
Classic worldwide localities
- Eureka District, Nevada, USA
- Tombstone, Arizona, USA
Field-hunting tip
Where it forms: In the oxidation zone of quartz-sulfide ores containing tellurides (mostly hessite) in small cavities and in fractures in quartz. If you start seeing mcalpineite, malachite, zn-bearing olivenite in float, you are in the right ground. Typical habit: microcrystalline aggregates, crusts, powdery coatings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify eurekadumpite?+
Where is eurekadumpite found?+
Is eurekadumpite safe to handle?+
What rocks look like eurekadumpite?+
What minerals are found with eurekadumpite?+
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Find eurekadumpite on the map
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