Hureaulite is a secondary phosphate mineral typically formed by the alteration of triphylite in granitic pegmatites. It is sought after by collectors for its attractive range of warm colors and distinct, well-formed glassy crystals.
Is this hureaulite?
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 hureaulite with a known reference. Hureaulite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: nearly white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, inclined towards greasy.
- 4Match the color rangeCompare against the expected color range: red, white, grayish white, yellowish white, reddish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: compact, fibrous, massive.
Often confused with
Hureaulite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hureaulite leaves nearly white, Fairfieldite leaves white; luster reads vitreous, inclined towards greasy on Hureaulite and pearly to subadamantine, vitreous on the {001} cleavage on Fairfieldite.
How to tell apart: Eosphorite is the harder of the two (Mohs 5 vs. 3.5); streak differs, so Hureaulite leaves nearly white, Eosphorite leaves white.
How to tell apart: Triplite is the harder of the two (Mohs 5-5.5 vs. 3.5); streak differs, so Hureaulite leaves nearly white, Triplite leaves white to brown.
Often found alongside hureaulite
Minerals reported to co-occur with hureaulite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺₅(PO₄)₂(PO₃OH)₂·4H₂O
- Mohs hardness
- 3.5
- Density
- 3.15-3.19 g/cm³
- Streak
- Nearly white
- Luster
- Vitreous, inclined towards greasy
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Compact, fibrous, massive
- Cleavage
- On {100}, good
- Rarity
- Uncommon
- Uses
- Collector, Mineralogical study
- Host rock
- A late-stage secondary mineral formed by alteration of primary phosphates in complex granite pegmatites
Where rockhounds find hureaulite
Classic worldwide localities
- Strickland quarry, Portland, Middlesex Co., and at Branchville, Fairfield Co., Connecticut, USA
- Fletcher and Palermo #1 mines, near North Groton, Grafton Co., New Hampshire, USA
- Emmons quarry, Greenwood, Oxford Co., Maine, USA
- Bull Moose and Tip Top mines, near Custer, and the White Elephant mine, near Pringle, Custer Co., South Dakota, USA
- Huréaux, St. Sylvestre, and in the La Vilate quarry, near Chanteloube, Haute-Vienne, France
- Mangualde pegmatite, near Mesquitela, Portugal
Field-hunting tip
Where it forms: A late-stage secondary mineral formed by alteration of primary phosphates in complex granite pegmatites. If you start seeing lithiophilite, triphylite, heterosite in float, you are in the right ground. Typical habit: compact, fibrous, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hureaulite?+
Where is hureaulite found?+
What rocks look like hureaulite?+
What minerals are found with hureaulite?+
What kind of rock does hureaulite form in?+
What is hureaulite used for?+
Find hureaulite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
