Yagiite is a rare sodium-rich member of the osumilite group, typically found as small, clear, hexagonal prismatic crystals within basaltic rocks. It is chemically distinct due to its high sodium content and is primarily a scientific rarity for mineral collectors. It is most famous for its occurrence in the Kogachi basalt in Okinawa, Japan.
Is this yagiite?
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 yagiite with a known reference. Yagiite sits at Mohs 5-6, 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: colorless.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: hexagonal prismatic crystals.
Often confused with
Yagiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Yagiite leaves white, Osumilite leaves blue-gray.
How to tell apart: Cordierite is the harder of the two (Mohs 7-7.5 vs. 5-6).
How to tell apart: Beryl is the harder of the two (Mohs 7.5-8 vs. 5-6).
Often found alongside yagiite
Minerals reported to co-occur with yagiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaMg₂(AlMg₂Si₁₂)O₃₀
- Mohs hardness
- 5-6
- Density
- 2.7 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Hexagonal
- Crystal habit
- Hexagonal prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In silicate inclusions of an iron meteorite, crystallized in a magnesium-rich environment
Where rockhounds find yagiite
Classic worldwide localities
- In the Colomera iron meteorite (type locality)
Field-hunting tip
Where it forms: In silicate inclusions of an iron meteorite, crystallized in a magnesium-rich environment. If you start seeing diopside, whitlockite, tridymite in float, you are in the right ground. Typical habit: hexagonal prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find yagiite on the map
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