Tuscanite is an extremely rare silicate mineral found primarily within volcanic ejecta blocks in Italy. It typically appears as small yellow to yellowish-colorless crystals and is prized specifically by advanced mineral collectors for its unique composition and limited occurrence.

Hardness

5.5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Tuscanite

Hardness: 5.5-6
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this tuscanite?

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 tuscanite with a known reference. Tuscanite sits at Mohs 5.5-6, 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: vitreous.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy.

Often confused with

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

Often found alongside tuscanite

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

All properties

Chemical formula: KCa₆(Si,Al)₁₀O₂₂(SO₄,CO₃)₂(OH)·H₂O
Mohs hardness: 5.5-6
Density: 2.83 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Platy
Cleavage: {100}, distinct
Rarity: Rare
Uses: Collector
Host rock: Within ejected blocks of metasomatized carbonate rocks in a pumice deposit

Where rockhounds find tuscanite

Classic worldwide localities

Casa Collina quarry, in the Latera caldera, Pitigliano, near Grosseto, Tuscany, and at Sacrofano, Lazio, Italy

Field-hunting tip

Where it forms: Within ejected blocks of metasomatized carbonate rocks in a pumice deposit. If you start seeing vesuvianite, andradite, grossular in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tuscanite?+

Mohs hardness is 5.5-6. Luster: vitreous. The streak is white. Common colors include colorless.

Where is tuscanite found?+

Notable localities include Casa Collina quarry, in the Latera caldera, Pitigliano, near Grosseto, Tuscany, and at Sacrofano, Lazio, Italy.

What rocks look like tuscanite?+

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

What minerals are found with tuscanite?+

Tuscanite commonly co-occurs with Vesuvianite, Andradite, Grossular, Pyroxene, Wollastonite, Anorthite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tuscanite form in?+

Where it forms: Within ejected blocks of metasomatized carbonate rocks in a pumice deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is tuscanite used for?+

Tuscanite is used in collector.

Find tuscanite on the map

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