Momoiite is a rare manganese-vanadium garnet species first discovered in Japan. It is prized by collectors for its vibrant yellow-green to emerald-green hue, caused by the presence of vanadium, and is typically found in manganese deposits or associated skarn environments.
Is this momoiite?
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 momoiite with a known reference. Momoiite sits at Mohs 6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dull green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: greenish yellow.
- 5Look at form & habitCrystal system: cubic. Typical habit: dodecahedral or trapezohedral crystals.
Often confused with
Momoiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Momoiite leaves dull green, Andradite leaves white; luster reads vitreous on Momoiite and adamantine to resinous, dull on Andradite.
How to tell apart: Streak differs, so Momoiite leaves dull green, Grossular leaves white.
How to tell apart: Streak differs, so Momoiite leaves dull green, Uvarovite leaves white.
Often found alongside momoiite
Minerals reported to co-occur with momoiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₃V₂(SiO₄)₃
- Mohs hardness
- 6.5
- Density
- 4.01 g/cm³
- Colors
- Streak
- Dull green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Dodecahedral or trapezohedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Product of the metamorphism of siliceous manganese-bearing rocks
Where rockhounds find momoiite
Classic worldwide localities
- Kurase mine, Ehime Prefecture, the Hokkejino mine, Kyoto Prefecture, the Fujii mine, Fukui Prefecture and from the Tanohata mine, Iwate Prefecture, Japan
Field-hunting tip
Where it forms: Product of the metamorphism of siliceous manganese-bearing rocks. If you start seeing rhodonite, calcite, tephroite in float, you are in the right ground. Typical habit: dodecahedral or trapezohedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify momoiite?+
Where is momoiite found?+
Is momoiite safe to handle?+
What rocks look like momoiite?+
What minerals are found with momoiite?+
What kind of rock does momoiite form in?+
What is momoiite used for?+
Find momoiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
