Tazzoliite is a rare barium-titanium silicate mineral found primarily in volcanic ejecta blocks at Mount Vesuvius. It typically forms as small, brown, elongated prismatic crystals embedded within alkaline volcanic rocks.

Hardness

5-5.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrarePerrierite Group family

Tazzoliite

Hardness: 5-5.5
Luster: Vitreous
Streak: White
Transparency: Translucent

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Is this tazzoliite?

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 tazzoliite with a known reference. Tazzoliite sits at Mohs 5-5.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Tazzoliite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Tazzoliite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: brown, yellowish-brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals.

Often confused with

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

mineral

Allanite

Mohs 5.5-6

How to tell apart: Streak differs — Tazzoliite leaves white, Allanite leaves gray; luster reads vitreous on Tazzoliite and submetallic on Allanite.

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Often found alongside tazzoliite

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

All properties

Chemical formula: Ba₂Ca(Ti,Fe³⁺,Mg,Mn)₄Ti₂(Si₂O₇)₂O₈
Mohs hardness: 5-5.5
Density: 4.28 g/cm³
Colors: Brown Yellowish-brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Volcanic Ejecta
Typical price: $50-300 per specimen

Where rockhounds find tazzoliite

Classic worldwide localities

Vesuvius, Italy
Monte Somma, Italy

Field-hunting tip

Look in volcanic ejecta country — that is the host setting where tazzoliite typically forms. If you start seeing sanidine, nepheline, pyroxene in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tazzoliite?+

Mohs hardness is 5-5.5. It typically shows a vitreous luster. The streak is white. Common colors include brown, yellowish-brown.

Where is tazzoliite found?+

Notable localities include Vesuvius, Italy; Monte Somma, Italy.

How much is tazzoliite 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 tazzoliite?+

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

What minerals are found with tazzoliite?+

Tazzoliite commonly co-occurs with Sanidine, Nepheline, Pyroxene. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tazzoliite form in?+

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

What is tazzoliite used for?+

Tazzoliite is used in collector.

Find tazzoliite on the map

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