Earlshannonite is a rare phosphate mineral primarily found as an alteration product in complex granite pegmatites. Collectors usually seek out its distinct brownish bladed crystals occurring in radial sprays or thin coatings on primary phosphate minerals.
Is this earlshannonite?
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 earlshannonite with a known reference. Earlshannonite 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. Earlshannonite leaves a pale brown streak.
- 3Read the lusterHold the specimen under a strong light. Earlshannonite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: brown, yellowish-brown, reddish-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed crystals, radial aggregates, crusts.
Often confused with
Earlshannonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Earlshannonite is noticeably harder (Mohs 3.5 vs. 1.5-2); streak differs, so Earlshannonite leaves pale brown, Vivianite leaves white to light blue.
How to tell apart: Streak differs, so Earlshannonite leaves pale brown, Ludlamite leaves white.
How to tell apart: Earlshannonite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Earlshannonite leaves pale brown, Santabarbaraite leaves amber; luster reads vitreous on Earlshannonite and vitreous to greasy on Santabarbaraite.
Often found alongside earlshannonite
Minerals reported to co-occur with earlshannonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺Fe³⁺₂(PO₄)₂(OH)₂·4H₂O
- Mohs hardness
- 3.5
- Density
- 2.9 g/cm³
- Streak
- Pale Brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed Crystals, Radial Aggregates, Crusts
- Cleavage
- Two, Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Granite Pegmatites
Where rockhounds find earlshannonite
Classic worldwide localities
- Big Chief Mine (South Dakota, USA)
- Hagendorf (Germany)
Field-hunting tip
Look in phosphate-rich granite pegmatites country, the host setting where earlshannonite typically forms. If you start seeing triphylite, sicklerite, rockbridgeite in float, you are in the right ground. Field specimens usually show a bladed crystals, radial aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify earlshannonite?+
Where is earlshannonite found?+
What rocks look like earlshannonite?+
What minerals are found with earlshannonite?+
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Find earlshannonite on the map
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