Ciprianiite is an extremely rare silicate mineral found in the volcanic ejecta of Italy. It typically forms as small, elongated prismatic crystals in cavities and is highly sought after by systematic mineral collectors due to its localized occurrence.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareHellandite Group family

Ciprianiite

Hardness: 5-6
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this ciprianiite?

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 ciprianiite with a known reference. Ciprianiite sits at Mohs 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: pale brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: anhedral grains, tabular.

Often confused with

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

mineral

Gadolinite-(Y)

Mohs 6.5-7

How to tell apart: Streak differs, so Ciprianiite leaves white, Gadolinite-(Y) leaves greenish gray.

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Often found alongside ciprianiite

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

All properties

Chemical formula: Ca₄(ThCa)Al(Be₀.₅□₁.₅)[B₄Si₄O₂₂](OH)₂
Mohs hardness: 5-6
Density: 3.75-3.85 g/cm³
Colors: Pale brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Anhedral grains, tabular
Cleavage: Fair to good on {100}
Rarity: Rare
Uses: Collector
Host rock: In miarolitic cavities and voids in alkali-syenitic pyroclastic ejecta

Where rockhounds find ciprianiite

Classic worldwide localities

Tre Croci, near Vetralla, Viterbo province, Latium, Italy

Field-hunting tip

Where it forms: In miarolitic cavities and voids in alkali-syenitic pyroclastic ejecta. If you start seeing sanidine, plagioclase, feldspathoid in float, you are in the right ground. Typical habit: anhedral grains, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ciprianiite?+

Mohs hardness is 5-6. Luster: vitreous. The streak is white. Common colors include pale brown.

Where is ciprianiite found?+

Notable localities include Tre Croci, near Vetralla, Viterbo province, Latium, Italy.

Is ciprianiite safe to handle?+

Ciprianiite contains beryllium and uranium or thorium and calls for real care. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like ciprianiite?+

Ciprianiite is most often confused with Gadolinite-(Y). A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ciprianiite?+

Ciprianiite commonly co-occurs with Sanidine, Plagioclase, Feldspathoid, Clinopyroxene, Clinoamphibole, Magnetite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ciprianiite form in?+

Where it forms: In miarolitic cavities and voids in alkali-syenitic pyroclastic ejecta. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ciprianiite used for?+

Ciprianiite is used in collector.

Find ciprianiite on the map

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