Johnwalkite is a rare phosphate mineral typically found in complex granite pegmatites. It usually forms small, yellowish-brown tabular crystals and is highly sought after by systematic mineral collectors due to its scarcity.
Is this johnwalkite?
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 johnwalkite with a known reference. Johnwalkite 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. Johnwalkite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Johnwalkite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to blocky crystals.
Often confused with
Johnwalkite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside johnwalkite
Minerals reported to co-occur with johnwalkite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Mn²⁺₄Nb₂O₂[(PO₄)₄]·4H₂O
- Mohs hardness
- 3.5
- Density
- 3.54 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Blocky Crystals
- Cleavage
- Distinct On {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find johnwalkite
Classic worldwide localities
- Tip Top mine, South Dakota, USA
- Mangualde mine, Portugal
Field-hunting tip
Look in granite pegmatites country — that is the host setting where johnwalkite typically forms. If you start seeing apatite, quartz, muscovite in float, you are in the right ground. Field specimens usually show a tabular to blocky crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find johnwalkite on the map
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