Triphylite is a phosphate mineral primarily found in lithium-rich granite pegmatites. It is often identified by its characteristic blue-green to grayish-blue color, though it readily alters to dark brown or black manganese-iron oxides when exposed to air.
Is this triphylite?
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 triphylite with a known reference. Triphylite 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 to grayish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to subresinous.
- 4Match the color rangeCompare against the expected color range: bluish gray, gray, brownish, blackish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, prismatic.
Often confused with
Triphylite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside triphylite
Minerals reported to co-occur with triphylite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- LiFePO₄
- Mohs hardness
- 4-5
- Density
- 3.50-3.58 g/cm³
- Colors
- Streak
- White to grayish white
- Luster
- Vitreous to subresinous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, prismatic
- Cleavage
- {100}, perfect; {010}, imperfect; {011}, interrupted
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- The most abundant primary phosphate in complex zoned granite pegmatites
Where rockhounds find triphylite
1 mapped spotsClassic worldwide localities
- G.E. Smith quarry, Newport, Sullivan Co., the Palermo #1 mine, near North Groton, Grafton Co., New Hampshire, USA
- Newry, Oxford Co., Maine, USA
- Dan Patch, Big Chief, and Hesnard mines, near Keystone, Pennington Co., and at the Bull Moose and Tip Top mines, near Custer, Custer Co., South Dakota, USA
- White Picacho district, Maricopa and Yavapai Cos., Arizona, USA
- Germany, from Hühnerkobel, near Zwiesel, and Hagendorf, Bavaria
- Sukula and Tammela, Finland
Field-hunting tip
Where it forms: The most abundant primary phosphate in complex zoned granite pegmatites. If you start seeing ferrisicklerite, heterosite, alluaudite in float, you are in the right ground. Typical habit: massive, prismatic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wisconsin. Start trip planning there.
Common questions
How do you identify triphylite?+
Where is triphylite found?+
Can I find triphylite in the United States?+
What rocks look like triphylite?+
What minerals are found with triphylite?+
What kind of rock does triphylite form in?+
What is triphylite used for?+
Find triphylite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
