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

No image

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, so 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, 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.