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 — that is 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.