Sphaerobertrandite is an exceptionally rare beryllium silicate mineral that typically forms distinct spherical or radial fibrous aggregates. It is structurally related to bertrandite and is primarily found in complex beryllium-rich pegmatite environments.
Is this sphaerobertrandite?
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 sphaerobertrandite with a known reference. Sphaerobertrandite 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: yellow, colorless, brownish white, white, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy, spherical.
Often confused with
Sphaerobertrandite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bertrandite is the harder of the two (Mohs 6-7 vs. 5).
How to tell apart: Sphaerobertrandite is noticeably harder (Mohs 5 vs. 3).
How to tell apart: Sphaerobertrandite is noticeably harder (Mohs 5 vs. 3.5-4).
Often found alongside sphaerobertrandite
Minerals reported to co-occur with sphaerobertrandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Be₃SiO₄(OH)₂
- Mohs hardness
- 5
- Density
- 2.46-2.54 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy, spherical
- Cleavage
- Perfect on {001}, another parallel to [001] 45° to (010)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In schlieren-like pegmatite occurring in eudialyte lujavrite near the margin of poikilitic nepheline-sodalite syenites (Mannepakhk Mountain)
Where rockhounds find sphaerobertrandite
Classic worldwide localities
- Mannepakhk and Sengischorr Mountains, Lovozero massif, Kola peninsula, Russia
- Qeqertaussaq, northern coast of Kangerluarsuk fjord, Ilimaussaq complex, South Greenland
- Western Tuften larvikite quarry, Tvedalen, Larvik, South Norway
- Hsianghualing, Hunan Province, China
Field-hunting tip
Where it forms: In schlieren-like pegmatite occurring in eudialyte lujavrite near the margin of poikilitic nepheline-sodalite syenites (Mannepakhk Mountain). If you start seeing epididymite, eudidymite, aegirine in float, you are in the right ground. Typical habit: platy, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sphaerobertrandite?+
Where is sphaerobertrandite found?+
Is sphaerobertrandite safe to handle?+
What rocks look like sphaerobertrandite?+
What minerals are found with sphaerobertrandite?+
What kind of rock does sphaerobertrandite form in?+
What is sphaerobertrandite used for?+
Find sphaerobertrandite on the map
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