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, 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.