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

mineralrare

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, 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.