Bertrandite is a primary ore of beryllium that commonly forms as delicate, tabular to prismatic crystals in cavities. It is frequently found as a secondary mineral replacing beryl in pegmatites or in hydrothermal deposits associated with fluorite and other beryllium minerals. Collectors value it for its sharp, glassy luster and complex crystal formations, though specimens require careful handling due to the toxicity of beryllium.
Is this bertrandite?
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 bertrandite with a known reference. Bertrandite sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bertrandite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Bertrandite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow, pale green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular to prismatic crystals, often as radiating clusters or pseudomorphs.
Often confused with
Bertrandite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Bertrandite is noticeably harder (Mohs 6-7 vs. 4.5-5).
How to tell apart: Bertrandite is noticeably harder (Mohs 6-7 vs. 3-3.5); luster reads vitreous on Bertrandite and adamantine on Cerussite.
Often found alongside bertrandite
Minerals reported to co-occur with bertrandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Be₄Si₂O₇(OH)₂
- Mohs hardness
- 6-7
- Density
- 2.59-2.60 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular to Prismatic Crystals, Often as Radiating Clusters or Pseudomorphs
- Cleavage
- Distinct in One Direction
- Rarity
- Uncommon
- Uses
- Collector, Ore of Beryllium
- Host rock
- Granite Pegmatites, Hydrothermal Veins, And Greisen Zones
- Typical price
- $10-100 per specimen depending on size and crystal quality
Where rockhounds find bertrandite
3 mapped spotsClassic worldwide localities
- Utah, USA
- Durango, Mexico
- Minas Gerais, Brazil
- Russia
- France
Field-hunting tip
Look in granite pegmatites, hydrothermal veins, and greisen zones country — that is the host setting where bertrandite typically forms. If you start seeing fluorite, beryl, phenakite in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, often as radiating clusters or pseudomorphs habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Colorado, Utah, Wisconsin — start trip planning there.
Common questions
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Find bertrandite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
