Isokite is a rare phosphate mineral typically found in complex granite pegmatites. It is often identified by its association with secondary phosphate minerals and its distinct monoclinic crystal structure, though it is usually found in massive or granular form.
Is this isokite?
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 isokite with a known reference. Isokite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Isokite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Isokite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, grayish, pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive, or as small prismatic crystals.
Often confused with
Isokite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside isokite
Minerals reported to co-occur with isokite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMg(PO₄)F
- Mohs hardness
- 4.5
- Density
- 3.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, Massive, Or as Small Prismatic Crystals
- Cleavage
- Good in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find isokite
Classic worldwide localities
- Isoka, Zambia
- Mangualde, Portugal
- Hagendorf, Germany
- Tip Top mine, USA
Field-hunting tip
Look in granite pegmatites country — that is the host setting where isokite typically forms. If you start seeing quartz, muscovite, beryl in float, you are in the right ground. Field specimens usually show a granular, massive, or as small prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find isokite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
