Farneseite is a rare member of the cancrinite group found within volcanic ejecta in the Alban Hills region of Italy. It typically occurs as small, colorless to white prismatic crystals and is primarily sought after by advanced mineral collectors specializing in rare zeolites and feldspathoids.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareCancrinite Group family

Farneseite

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

No image

Is this farneseite?

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 farneseite with a known reference. Farneseite 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. Farneseite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Farneseite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: trigonal. Typical habit: prismatic crystals.

Often confused with

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

Often found alongside farneseite

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

All properties

Chemical formula: (Na,Ca,K)₈Al₆Si₆O₂₄(SO₄,CO₃,Cl,OH)₂·nH₂O
Mohs hardness: 5-6
Density: 2.35 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Prismatic Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Volcanic Ejecta
Typical price: $50-300 per specimen

Where rockhounds find farneseite

Classic worldwide localities

Alban Hills, Italy

Field-hunting tip

Look in volcanic ejecta country — that is the host setting where farneseite typically forms. If you start seeing leucite, nepheline, garnet 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 farneseite?+

Mohs hardness is 5-6. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless.

Where is farneseite found?+

Notable localities include Alban Hills, Italy.

How much is farneseite 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 farneseite?+

Farneseite is most often confused with Cancrinite, Vishnevite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with farneseite?+

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

What kind of rock does farneseite form in?+

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

What is farneseite used for?+

Farneseite is used in collector.

Find farneseite on the map

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