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 7-7.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Momoiite leaves a dull green streak.
- 3Read the lusterHold the specimen under a strong light. Momoiite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow-green, emerald-green, yellowish-brown.
- 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 to dull on Andradite.
How to tell apart: Streak differs, so Momoiite leaves dull green, Grossularite Garnet 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
- (Mn²⁺,Ca)₃(V³⁺,Al)₂Si₃O₁₂
- Mohs hardness
- 7-7.5
- Density
- 3.75-3.85 g/cm³
- Streak
- Dull Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Dodecahedral or Trapezohedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese-rich Metamorphic Rocks and Skarns
Where rockhounds find momoiite
Classic worldwide localities
- Fujii mine, Japan
- Kuruman district, South Africa
- Tanohata mine, Japan
Field-hunting tip
Look in manganese-rich metamorphic rocks and skarns country, the host setting where momoiite typically forms. If you start seeing rhodochrosite, quartz, spessartine in float, you are in the right ground. Field specimens usually show a dodecahedral or trapezohedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find momoiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
