Akaogiite is a rare monoclinic polymorph of titanium dioxide that forms as a high-pressure alteration product. It is primarily found as microscopic inclusions or thin platy crystals within granite pegmatites and is scientifically significant for its unique structural arrangement compared to more common TiO₂ polymorphs.
Is this akaogiite?
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 akaogiite with a known reference. Akaogiite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Akaogiite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Akaogiite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals.
Often confused with
Akaogiite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Akaogiite leaves white, Anatase leaves white to pale yellow; luster reads submetallic on Akaogiite and adamantine on Anatase.
How to tell apart: Streak differs — Akaogiite leaves white, Rutile leaves pale brown to yellow; luster reads submetallic on Akaogiite and metallic to adamantine on Rutile.
How to tell apart: Streak differs — Akaogiite leaves white, Brookite leaves white to yellowish-white.
Often found alongside akaogiite
Minerals reported to co-occur with akaogiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- TiO₂
- Mohs hardness
- 6
- Density
- 4.23 g/cm³
- Streak
- White
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- n/a
Where rockhounds find akaogiite
Classic worldwide localities
- Suishoyama, Fukushima Prefecture, Japan
Field-hunting tip
Look in granite pegmatites country — that is the host setting where akaogiite typically forms. If you start seeing quartz, feldspar, anatase in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find akaogiite on the map
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