Jahnsite-(NaMnMg) is a rare phosphate mineral typically found as secondary crusts or small crystals in the alteration zones of granite pegmatites. Collectors often find these alongside other phosphate species where primary minerals like triphylite have undergone chemical weathering.
Is this jahnsite-(namnmg)?
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-(namnmg) with a known reference. Jahnsite-(NaMnMg) 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-(NaMnMg) leaves a very pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Jahnsite-(NaMnMg) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, orange-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to prismatic crystals, often as small crusts or aggregates.
Often confused with
Jahnsite-(NaMnMg) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside jahnsite-(namnmg)
Minerals reported to co-occur with jahnsite-(namnmg). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaMnMg₂Fe³⁺₂(PO₄)₄(OH)₂·8H₂O
- Mohs hardness
- 4
- Density
- 2.7-2.9 g/cm³
- Colors
- Streak
- Very Pale Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Prismatic Crystals, Often as Small Crusts or Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Granite Pegmatites
Where rockhounds find jahnsite-(namnmg)
Classic worldwide localities
- Tip Top Mine, South Dakota, USA
- Palermo No. 1 Mine, New Hampshire, USA
- Bull Moose Mine, South Dakota, USA
Field-hunting tip
Look in phosphate-rich granite pegmatites country, the host setting where jahnsite-(namnmg) typically forms. If you start seeing triphylite, apatite, rockbridgeite in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, often as small crusts or aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify jahnsite-(namnmg)?+
Where is jahnsite-(namnmg) found?+
What rocks look like jahnsite-(namnmg)?+
What minerals are found with jahnsite-(namnmg)?+
What kind of rock does jahnsite-(namnmg) form in?+
What is jahnsite-(namnmg) used for?+
Find jahnsite-(namnmg) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
