Goslarite is a hydrated zinc sulfate that typically forms as a secondary efflorescence in mines where zinc-rich sulfide ores have oxidized. It is highly unstable in dry air and will rapidly dehydrate into a white powder, so collectors must keep specimens in airtight, humidity-controlled containers to maintain their crystal structure.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralcommon

Goslarite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this goslarite?

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 goslarite with a known reference. Goslarite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Goslarite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Goslarite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, blue, green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular or fibrous crusts, efflorescences, stalactitic.

Often confused with

Goslarite vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside goslarite

Minerals reported to co-occur with goslarite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: ZnSO₄·7H₂O
Mohs hardness: 2
Density: 1.95-1.97 g/cm³
Colors: Colorless White Blue Green
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Acicular or Fibrous Crusts, Efflorescences, Stalactitic
Cleavage: Perfect On {010}
Rarity: Common
Uses: Collector
Host rock: Oxidized Zones of Zinc-rich Hydrothermal Ore Deposits
Typical price: $10-60 per specimen

Where rockhounds find goslarite

Classic worldwide localities

Goslar, Germany
Chile
Spain
United States
Mexico

Field-hunting tip

Look in oxidized zones of zinc-rich hydrothermal ore deposits country, the host setting where goslarite typically forms. If you start seeing sphalerite, pyrite, melanterite in float, you are in the right ground. Field specimens usually show a acicular or fibrous crusts, efflorescences, stalactitic habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify goslarite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, blue, green.

Where is goslarite found?+

Notable localities include Goslar, Germany; Chile; Spain; United States; Mexico.

How much is goslarite worth?+

Typical asking prices fall in the range of $10-60 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is goslarite safe to handle?+

It contains toxic constituents. Contains zinc and sulfates; soluble in water and can cause irritation. Handle with care, avoid ingestion or prolonged skin contact, and store in a sealed container to prevent dehydration and crumbling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like goslarite?+

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

What minerals are found with goslarite?+

Goslarite commonly co-occurs with Sphalerite, Pyrite, Melanterite, Chalcanthite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does goslarite form in?+

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

What is goslarite used for?+

Goslarite is used in collector.

Find goslarite on the map

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