Jahnsite-(CaMnMn) is a rare phosphate mineral typically found in complex granite pegmatites as a late-stage alteration product. It is primarily sought after by advanced collectors for its aesthetic small, amber-colored crystals that form in vugs alongside other rarer phosphate species.
Is this jahnsite-(camnmn)?
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-(camnmn) with a known reference. Jahnsite-(CaMnMn) 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brownish yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to prismatic crystals, often as drusy coatings or small clusters.
Often confused with
Jahnsite-(CaMnMn) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside jahnsite-(camnmn)
Minerals reported to co-occur with jahnsite-(camnmn). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMn²⁺Mn²⁺₂Fe³⁺₂ (PO₄)₄(OH)₂·8H₂O
- Mohs hardness
- ~4
- Density
- 2.78 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to prismatic crystals, often as drusy coatings or small clusters
- Cleavage
- Poor on {001}, a parting
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late stage hydrothermal decomposition product of primary phosphate minerals in complex granite pegmatites
Where rockhounds find jahnsite-(camnmn)
Classic worldwide localities
- Bell pit, Newry, and on Mt. Mica, near Paris, Oxford Co., Maine, USA
- Mangualde pegmatite, near Mesquitela, Portugal
Field-hunting tip
Where it forms: A late stage hydrothermal decomposition product of primary phosphate minerals in complex granite pegmatites. If you start seeing phosphosiderite, zodacite, varulite in float, you are in the right ground. Typical habit: tabular to prismatic crystals, often as drusy coatings or small clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify jahnsite-(camnmn)?+
Where is jahnsite-(camnmn) found?+
What rocks look like jahnsite-(camnmn)?+
What minerals are found with jahnsite-(camnmn)?+
What kind of rock does jahnsite-(camnmn) form in?+
What is jahnsite-(camnmn) used for?+
Find jahnsite-(camnmn) on the map
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