Gayite is a rare phosphate mineral typically found as small, fibrous radial clusters in complex granite pegmatites. Collectors generally search for it in association with secondary phosphate minerals in the inner zones of zoned pegmatites.
Is this gayite?
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 gayite with a known reference. Gayite 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. Streak: olive green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: greenish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous radial aggregates, encrustations.
Often confused with
Gayite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside gayite
Minerals reported to co-occur with gayite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaMnFe₅(PO₄)₄(OH)₆·2H₂O
- Mohs hardness
- 4-5
- Density
- 3.15 g/cm³
- Colors
- Streak
- Olive green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous radial aggregates, encrustations
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In vugs in hydrothermal apatite-(CaF) in a zoned granitic pegmatite
Where rockhounds find gayite
Classic worldwide localities
- Gigante granitic pegmatite, 18.45 km west-southwest of Tanti, Punilla department, Córdoba province, Argentina
Field-hunting tip
Where it forms: In vugs in hydrothermal apatite-(CaF) in a zoned granitic pegmatite. If you start seeing morinite, natrodufrénite, quartz in float, you are in the right ground. Typical habit: fibrous radial aggregates, encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gayite?+
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Find gayite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
