Hurlbutite is a rare beryllium phosphate mineral typically found in granitic pegmatites. It often forms colorless or pale, vitreous crystals that can be easily mistaken for quartz or danburite without chemical testing.
Is this hurlbutite?
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 hurlbutite with a known reference. Hurlbutite sits at Mohs 6, 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 to greasy.
- 4Match the color rangeCompare against the expected color range: colorless, greenish white, yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic.
Often confused with
Hurlbutite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside hurlbutite
Minerals reported to co-occur with hurlbutite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaBe₂P₂O₈
- Mohs hardness
- 6
- Density
- 2.877 g/cm³
- Streak
- White
- Luster
- Vitreous to greasy
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- A late-stage mineral in complex granite pegmatites; observed as an alteration product of beryl
Where rockhounds find hurlbutite
Classic worldwide localities
- G.E. Smith mine, Newport, Sullivan Co., and at the Beauregard pegmatite, Gilsum, Cheshire Co., New Hampshire, USA
- Black Mountain quarry, Rumford, Oxford Co., Maine, USA
- Tip Top mine, 8.5 km southwest of Custer, Custer Co., South Dakota, USA
- Viitaniemi pegmatite, near Eräjärvi, Finland
- Norrö pegmatite, on Rånö Island, and from near Kapelludden, Utö Island, Sweden
- Otov, near Ronsperk, Czech Republic
Field-hunting tip
Where it forms: A late-stage mineral in complex granite pegmatites; observed as an alteration product of beryl. If you start seeing triphylite, siderite, muscovite 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 hurlbutite?+
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Is hurlbutite safe to handle?+
What rocks look like hurlbutite?+
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Find hurlbutite on the map
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