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.
Is this farneseite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch farneseite with a known reference. Farneseite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic.
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
- Na₄₆Ca₁₀(Si₄₂Al₄₂O₁₆₈)(SO₄)₁₂·6H₂O
- Mohs hardness
- 5
- Density
- 2.425 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic
- Cleavage
- Poor on {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In vugs between interlocking sanidine within a syenitic pyroclastic rock
Where rockhounds find farneseite
Classic worldwide localities
- Farnese, Viterbo Province (north of Rome), Italy
Field-hunting tip
Where it forms: In vugs between interlocking sanidine within a syenitic pyroclastic rock. If you start seeing sanidine, andradite, clinopyroxene in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify farneseite?+
Where is farneseite found?+
What rocks look like farneseite?+
What minerals are found with farneseite?+
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Find farneseite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
