Ziesite is a rare copper vanadate mineral typically found as a volcanic sublimates in fumarolic deposits. It is known for its distinctive yellow to orange color and often occurs as thin, platy crystals on volcanic rock surfaces.

Hardness

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Translucent

mineralrare

Ziesite

Hardness: 3
Luster: Vitreous
Streak: Yellow
Transparency: Translucent

Is this ziesite?

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 ziesite with a known reference. Ziesite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Ziesite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Ziesite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, orange, red-orange.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals, crusts.

Often confused with

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

How to tell apart: Streak differs, so Ziesite leaves yellow, Bloedite leaves white.

How to tell apart: Streak differs, so Ziesite leaves yellow, Thénardite leaves white.

Compare →

Often found alongside ziesite

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

All properties

Chemical formula: Cu₂V₂O₇
Mohs hardness: 3
Density: 3.84 g/cm³
Colors: Yellow Orange Red-orange
Streak: Yellow
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Volcanic Fumaroles
Typical price: $50-300+ for micro-specimens

Where rockhounds find ziesite

Classic worldwide localities

Izalco Volcano, El Salvador

Field-hunting tip

Look in volcanic fumaroles country, the host setting where ziesite typically forms. If you start seeing thenardite, vanthoffite, bloedite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ziesite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, orange, red-orange.

Where is ziesite found?+

Notable localities include Izalco Volcano, El Salvador.

How much is ziesite worth?+

Typical asking prices fall in the range of $50-300+ for micro-specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is ziesite safe to handle?+

It contains toxic constituents. Contains copper and vanadium, which are toxic. Avoid inhalation of dust or ingestion; wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like ziesite?+

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

What minerals are found with ziesite?+

Ziesite commonly co-occurs with thenardite, vanthoffite, bloedite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ziesite form in?+

Ziesite typically forms in volcanic fumaroles. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ziesite used for?+

Ziesite is used in collector.

Find ziesite on the map

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