Zircosulfate is an extremely rare zirconium sulfate mineral that typically forms as a secondary encrustation or in fumarolic environments. It appears as small, fragile, colorless to white tabular crystals that are highly soluble in water, making it a challenging mineral to collect and store.

Hardness

2.5-3

Mohs

Luster

Dull

Streak

White

Transparency

Semitransparent

mineralrare

Zircosulfate

Hardness: 2.5-3
Luster: Dull
Streak: White
Transparency: Semitransparent

Is this zircosulfate?

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 zircosulfate with a known reference. Zircosulfate sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: dull.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals.

Often confused with

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

mineral

Gypsum

Mohs 1.5-2

How to tell apart: Luster reads dull on Zircosulfate and subvitreous, pearly on {010} cleavages, silky if fibrous on Gypsum.

How to tell apart: Luster reads dull on Zircosulfate and vitreous, silky in fibrous aggregates on Epsomite.

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Often found alongside zircosulfate

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

All properties

Chemical formula: Zr(SO₄)₂·4H₂O
Mohs hardness: 2.5-3
Density: 2.85 g/cm³
Colors: White Colorless
Streak: White
Luster: Dull
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Tabular crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: In a cavity in intensely hydrothermally altered nepheline syenite pegmatite, perhaps formed by acid sulfatic solutions attacking eudialyte

Where rockhounds find zircosulfate

Classic worldwide localities

Korgeredaba alkalic massif, Sangilen Upland, southeastern Tuva, Russia

Field-hunting tip

Where it forms: In a cavity in intensely hydrothermally altered nepheline syenite pegmatite, perhaps formed by acid sulfatic solutions attacking eudialyte. If you start seeing hisingerite, smithsonite, limonite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify zircosulfate?+

Mohs hardness is 2.5-3. Luster: dull. The streak is white. Common colors include white, colorless.

Where is zircosulfate found?+

Notable localities include Korgeredaba alkalic massif, Sangilen Upland, southeastern Tuva, Russia.

What rocks look like zircosulfate?+

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

What minerals are found with zircosulfate?+

Zircosulfate commonly co-occurs with Hisingerite, Smithsonite, Limonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does zircosulfate form in?+

Where it forms: In a cavity in intensely hydrothermally altered nepheline syenite pegmatite, perhaps formed by acid sulfatic solutions attacking eudialyte. Working float back to the host body is the standard way to chase a fresh occurrence.

What is zircosulfate used for?+

Zircosulfate is used in collector.

Find zircosulfate on the map

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