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.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareKieserite Group family

Gunningite

Hardness: 2.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this gunningite?

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 gunningite with a known reference. Gunningite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Gunningite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Gunningite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale yellow.
5
Look at form & habit
Crystal 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: (Zn,Mn)SO₄·H₂O
Mohs hardness: 2.5
Density: 3.2 g/cm³
Colors: White Colorless Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Encrustations, Granular, Efflorescent Coatings
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Zinc-bearing Hydrothermal Sulfide Ore Deposits
Typical price: $20-100 thumbnail

Where rockhounds find gunningite

Classic worldwide localities

Keno Hill, Yukon Territory, Canada
Broken Hill, New South Wales, Australia
San Juan Mountains, Colorado, USA
Lavrion District, Greece

Field-hunting tip

Look in oxidized zones of zinc-bearing hydrothermal sulfide ore deposits country, the host setting where gunningite typically forms. If you start seeing sphalerite, goslarite, szomolnokite in float, you are in the right ground. Field specimens usually show a encrustations, granular, efflorescent coatings habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify gunningite?+

Mohs hardness is 2.5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pale yellow.

Where is gunningite found?+

Notable localities include Keno Hill, Yukon Territory, Canada; Broken Hill, New South Wales, Australia; San Juan Mountains, Colorado, USA; Lavrion District, Greece.

How much is gunningite worth?+

Typical asking prices fall in the range of $20-100 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

Is gunningite safe to handle?+

It contains toxic constituents. Contains zinc and manganese; avoid inhalation of dust or ingestion. Wash hands thoroughly after handling as it is a soluble sulfate. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like gunningite?+

Gunningite is most often confused with Szomolnokite, Epsomite, Goslarite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with gunningite?+

Gunningite commonly co-occurs with Sphalerite, Goslarite, Szomolnokite, Anglesite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gunningite form in?+

Gunningite typically forms in oxidized zones of zinc-bearing hydrothermal sulfide ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is gunningite used for?+

Gunningite is used in collector.

Find gunningite on the map

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