Tvedalite is a rare beryllium-bearing silicate mineral typically found as delicate, radiating spherical aggregates. It is most famous for its discovery in the alkaline igneous rocks of the Tvedalen area in Norway, often appearing as coatings or small balls in pegmatite cavities. Collectors prize it for its unique habit and rarity in mineral suites.
Is this tvedalite?
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 tvedalite with a known reference. Tvedalite sits at Mohs 4.5, 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: white, pale gray, beige.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: spherulitic aggregates, radial clusters.
Often confused with
Tvedalite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside tvedalite
Minerals reported to co-occur with tvedalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄Be₃Si₆O₁₇(OH)₄·3H₂O
- Mohs hardness
- 4.5
- Density
- 2.541 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Spherulitic aggregates, radial clusters
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In nepheline syenite pegmatite
Where rockhounds find tvedalite
Classic worldwide localities
- Vevja quarry, Tvedalen, Norway
Field-hunting tip
Where it forms: In nepheline syenite pegmatite. If you start seeing chiavennite, analcime, natrolite in float, you are in the right ground. Typical habit: spherulitic aggregates, radial clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tvedalite?+
Where is tvedalite found?+
Is tvedalite safe to handle?+
What rocks look like tvedalite?+
What minerals are found with tvedalite?+
What kind of rock does tvedalite form in?+
What is tvedalite used for?+
Find tvedalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
