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.

Hardness

7-7.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareGarnet Group family

Momoiite

Hardness: 7-7.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this momoiite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try 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.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Momoiite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Momoiite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow-green, emerald-green, yellowish-brown.
5
Look at form & habit
Crystal 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.

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
Colors: Yellow-green Emerald-green Yellowish-brown
Streak: White
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
Typical price: $50-500 per specimen depending on size and intensity of green color

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 — that is 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

How do you identify momoiite?+

Mohs hardness is 7-7.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow-green, emerald-green, yellowish-brown.

Where is momoiite found?+

Notable localities include Fujii mine, Japan; Kuruman district, South Africa; Tanohata mine, Japan.

How much is momoiite worth?+

Typical asking prices fall in the range of $50-500 per specimen depending on size and intensity of green color. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like momoiite?+

Momoiite is most often confused with Andradite, Grossularite Garnet, Uvarovite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with momoiite?+

Momoiite commonly co-occurs with Rhodochrosite, Quartz, Spessartine, Hausmannite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does momoiite form in?+

Momoiite typically forms in manganese-rich metamorphic rocks and skarns. Working float back to the host body is the standard way to chase a fresh occurrence.

What is momoiite used for?+

Momoiite is used in collector.

Find momoiite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.