Jahnsite-(CaMnFe) is a rare secondary phosphate mineral typically found in the oxidized zones of granite pegmatites. Collectors look for its characteristic yellowish-brown tabular crystals occurring in small cavities with other phosphate minerals.
Is this jahnsite-(camnfe)?
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 jahnsite-(camnfe) with a known reference. Jahnsite-(CaMnFe) sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Jahnsite-(CaMnFe) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Jahnsite-(CaMnFe) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to prismatic crystals, often as tiny crusts or aggregates.
Often confused with
Jahnsite-(CaMnFe) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Jahnsite-(CaMnFe) is noticeably harder (Mohs 4 vs. 2.5); streak differs, so Jahnsite-(CaMnFe) leaves white, Whitmoreite leaves yellow-brown.
How to tell apart: Jahnsite-(CaMnFe) is noticeably harder (Mohs 4 vs. 3).
How to tell apart: Jahnsite-(CaMnFe) is noticeably harder (Mohs 4 vs. 1.5-2).
Often found alongside jahnsite-(camnfe)
Minerals reported to co-occur with jahnsite-(camnfe). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMnFe²⁺₂(H₂O)₈Fe³⁺₂(PO₄)₄(OH)₂
- Mohs hardness
- 4
- Density
- 2.84 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Prismatic Crystals, Often as Tiny Crusts or Aggregates
- Cleavage
- [Good On {001}] [by Analogy to Jahnsite-(CaMnMg)]
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Phosphate-rich Granite Pegmatites
Where rockhounds find jahnsite-(camnfe)
Classic worldwide localities
- Palermo No. 1 Mine, USA
- Tip Top Mine, USA
- Bull Moose Mine, USA
Field-hunting tip
Look in phosphate-rich granite pegmatites country, the host setting where jahnsite-(camnfe) typically forms. If you start seeing triphylite, sicklerite, fairfieldite in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, often as tiny crusts or aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify jahnsite-(camnfe)?+
Where is jahnsite-(camnfe) found?+
What rocks look like jahnsite-(camnfe)?+
What minerals are found with jahnsite-(camnfe)?+
What kind of rock does jahnsite-(camnfe) form in?+
What is jahnsite-(camnfe) used for?+
Find jahnsite-(camnfe) on the map
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