Utahite is a rare magnesium copper zinc hydroxide, typically pale blue to blue-green. It is associated with cesbronite and quartz. It was first described from the mine dumps of the Centennial Eureka mine, Tintic district, Juab Co., Utah, USA.
Is this utahite?
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 utahite with a known reference. Utahite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Utahite leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Utahite typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: pale blue, blue-green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy crystals, crusts, tabular.
Often confused with
Utahite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Utahite is noticeably harder (Mohs 4-5 vs. 2.5-3); streak differs, so Utahite leaves pale blue, Copiapite leaves yellow; luster reads vitreous to pearly on Utahite and pearly on Copiapite.
How to tell apart: Streak differs, so Utahite leaves pale blue, Jarosite leaves yellow; luster reads vitreous to pearly on Utahite and vitreous on Jarosite.
Often found alongside utahite
Minerals reported to co-occur with utahite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgCu²⁺₄Zn₂Te⁶⁺₃O₁₄(OH)₄·6H₂O
- Mohs hardness
- 4-5
- Density
- 5.33 g/cm³
- Colors
- Streak
- Pale Blue
- Luster
- Vitreous to Pearly
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Platy Crystals, Crusts, Tabular
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Ore Deposits
Where rockhounds find utahite
Classic worldwide localities
- Gold Hill, Tooele County, Utah, USA
- Tintic district, Juab County, Utah, USA
Field-hunting tip
Look in oxidized hydrothermal ore deposits country, the host setting where utahite typically forms. If you start seeing jarosite, malachite, brochantite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, tabular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify utahite?+
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Find utahite on the map
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