Guarinoite is a rare secondary sulfate mineral occurring as fine, needle-like acicular crystals or radial tufts. It is primarily identified by its distinctive blue color and its association with secondary zinc minerals in weathered ore zones.

Hardness

Mohs

Luster

Vitreous

Streak

Pale Blue

Transparency

Translucent

mineralrareMixite Group family

Guarinoite

Hardness: 3
Luster: Vitreous
Streak: Pale Blue
Transparency: Translucent

Is this guarinoite?

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 guarinoite with a known reference. Guarinoite 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. Guarinoite leaves a pale blue streak.
3
Read the luster
Hold the specimen under a strong light. Guarinoite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: blue, greenish-blue.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: acicular crystals, fibrous tufts.

Often confused with

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

mineral

Mixite

Mohs 3-4

How to tell apart: Streak differs — Guarinoite leaves pale blue, Mixite leaves white.

Compare →

Often found alongside guarinoite

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

All properties

Chemical formula: (Zn,Cu)₆(SO₄)(OH,Cl)₁₀·5H₂O
Mohs hardness: 3
Density: 4.2 g/cm³
Colors: Blue Greenish-blue
Streak: Pale Blue
Luster: Vitreous
Transparency: Translucent
Crystal system: Hexagonal
Crystal habit: Acicular Crystals, Fibrous Tufts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Hydrothermal Lead-zinc Deposits
Typical price: $50-300 per specimen

Where rockhounds find guarinoite

Classic worldwide localities

Sa Duchessa Mine, Sardinia, Italy

Field-hunting tip

Look in oxidized hydrothermal lead-zinc deposits country — that is the host setting where guarinoite typically forms. If you start seeing smithsonite, hemimorphite, linarite in float, you are in the right ground. Field specimens usually show a acicular crystals, fibrous tufts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify guarinoite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is pale blue. Common colors include blue, greenish-blue.

Where is guarinoite found?+

Notable localities include Sa Duchessa Mine, Sardinia, Italy.

How much is guarinoite 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.

Is guarinoite safe to handle?+

It contains toxic constituents. Contains heavy metals; wash hands thoroughly after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like guarinoite?+

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

What minerals are found with guarinoite?+

Guarinoite commonly co-occurs with Smithsonite, Hemimorphite, Linarite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does guarinoite form in?+

Guarinoite typically forms in oxidized hydrothermal lead-zinc deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is guarinoite used for?+

Guarinoite is used in collector.

Find guarinoite on the map

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