Gunningite is a rare secondary zinc sulfate mineral that typically forms as a white efflorescent crust on weathered sphalerite. Because it is highly water-soluble, it is almost exclusively found in arid climates or protected mine environments where it remains dry.
Is this gunningite?
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 gunningite with a known reference. Gunningite sits at Mohs ~2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: encrustations, granular, efflorescent coatings.
Often confused with
Gunningite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside gunningite
Minerals reported to co-occur with gunningite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ZnSO₄·H₂O
- Mohs hardness
- ~2.5
- Density
- 3.195 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Encrustations, granular, efflorescent coatings
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of rare occurrence in dry areas of the oxidized portions of sphalerite-bearing deposits; occurs also as a post-mining efflorescence on museum specimens
Where rockhounds find gunningite
Classic worldwide localities
- Goldstrike mine, Lynn district, Eureka Co., Nevada, and at Bisbee, Cochise Co., Arizona, USA
- Keno Hill–Galena Hill district, about 56 km northeast of Mayo, Yukon Territory, Canada
- Willett mine, near Lardeau, British Columbia, Canada
- Brunswick No. 2 mine, Bathurst, New Brunswick, Canada
- Les Vallettes, Valais, Switzerland
- Kamariza mine, Laurium, Greece
Field-hunting tip
Where it forms: Of rare occurrence in dry areas of the oxidized portions of sphalerite-bearing deposits; occurs also as a post-mining efflorescence on museum specimens. If you start seeing sphalerite, scorodite, gypsum in float, you are in the right ground. Typical habit: encrustations, granular, efflorescent coatings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gunningite?+
Where is gunningite found?+
Is gunningite safe to handle?+
What rocks look like gunningite?+
What minerals are found with gunningite?+
What kind of rock does gunningite form in?+
What is gunningite used for?+
Find gunningite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
