Whitmoreite is a rare iron phosphate mineral typically found as brown, bladed, or radial crystal clusters in oxidized phosphate zones of pegmatites. It is highly valued by advanced micromount collectors due to its distinct, well-defined crystal habit and vibrant brown color. It is primarily identified by its occurrence in specific secondary phosphate assemblages.
Is this whitmoreite?
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 whitmoreite with a known reference. Whitmoreite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to subadamantine.
- 4Match the color rangeCompare against the expected color range: brown, greenish brown, light yellow brown, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, aggregates, radial.
Often confused with
Whitmoreite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside whitmoreite
Minerals reported to co-occur with whitmoreite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺Fe³⁺₂(PO₄)₂(OH)₂·4H₂O
- Mohs hardness
- 3
- Density
- 2.87 g/cm³
- Colors
- Streak
- Yellow-brown
- Luster
- Vitreous to subadamantine
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, aggregates, radial
- Cleavage
- On {100}, fair
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in complex zoned granite pegmatites
Where rockhounds find whitmoreite
Classic worldwide localities
- Palermo #1 mine, North Groton, Grafton Co., and at the Fitzgibbon mine, Alstead, Cheshire Co., New Hampshire, USA
- Bell Pit, Newry, Oxford Co., Maine, USA
- Big Chief mine, one km south of Glendale, Pennington Co., and the Tip Top mine, 8.5 km southwest of Custer, Custer Co., South Dakota, USA
- Gravel Hill mine, Perranzabuloe, Cornwall, England
- Bendada pegmatite, near Guarda, Portugal
- Hagendorf, and Hühnerkobel, near Zwiesel, Bavaria, Germany
Field-hunting tip
Where it forms: A secondary mineral in complex zoned granite pegmatites. If you start seeing siderite, triphylite, ludlamite in float, you are in the right ground. Typical habit: acicular, aggregates, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify whitmoreite?+
Where is whitmoreite found?+
What rocks look like whitmoreite?+
What minerals are found with whitmoreite?+
What kind of rock does whitmoreite form in?+
What is whitmoreite used for?+
Find whitmoreite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
