Minguzzite is an extremely rare iron oxalate mineral typically found in guano-rich environments or specific fumarolic conditions. It usually appears as small, emerald-green tabular crystals or fine crusts that are highly sensitive to moisture and light.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrarenull family

Minguzzite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this minguzzite?

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

Often confused with

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

Often found alongside minguzzite

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

All properties

Chemical formula: K₃Fe(C₂O₄)₃·3H₂O
Mohs hardness: 2-3
Density: 2.12 g/cm³
Colors: Green
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Crystalline Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Guano Deposits, Fumaroles
Typical price: $50-300 per specimen

Where rockhounds find minguzzite

Classic worldwide localities

Tuscany, Italy
Czech Republic

Field-hunting tip

Look in guano deposits, fumaroles country — that is the host setting where minguzzite typically forms. If you start seeing whewellite, oxammite in float, you are in the right ground. Field specimens usually show a tabular crystals, crystalline crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify minguzzite?+

Mohs hardness is 2-3. It typically shows a vitreous luster. The streak is white. Common colors include green.

Where is minguzzite found?+

Notable localities include Tuscany, Italy; Czech Republic.

How much is minguzzite worth?+

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

What rocks look like minguzzite?+

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

What minerals are found with minguzzite?+

Minguzzite commonly co-occurs with Whewellite, Oxammite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does minguzzite form in?+

Minguzzite typically forms in guano deposits, fumaroles. Working float back to the host body is the standard way to chase a fresh occurrence.

What is minguzzite used for?+

Minguzzite is used in collector.

Find minguzzite on the map

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