Udinaite is an extremely rare magnesium-aluminum silicate mineral found in high-temperature fumarole deposits. It typically occurs as small, pale yellow octahedral crystals associated with volcanic sublimation products.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareSpinel Group family

Udinaite

Hardness: 6
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this udinaite?

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 udinaite with a known reference. Udinaite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Udinaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Udinaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, pale yellow.
5
Look at form & habit
Crystal system: cubic. Typical habit: octahedral crystals.

Often confused with

Udinaite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Spinel

Mohs 8

How to tell apart: Spinel is the harder of the two (Mohs 8 vs. 6).

How to tell apart: Streak differs — Udinaite leaves white, Magnesioferrite leaves black; luster reads vitreous on Udinaite and metallic on Magnesioferrite.

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Often found alongside udinaite

Minerals reported to co-occur with udinaite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: NaMg₄(Al₄Mg₂)Si₂O₁₈F
Mohs hardness: 6
Density: 3.16 g/cm³
Colors: Yellow Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Cubic
Crystal habit: Octahedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Volcanic Fumaroles
Typical price: $100-500 per specimen

Where rockhounds find udinaite

Classic worldwide localities

Tolbachik volcano, Kamchatka, Russia

Field-hunting tip

Look in volcanic fumaroles country — that is the host setting where udinaite typically forms. If you start seeing tenorite, hematite, langbeinite in float, you are in the right ground. Field specimens usually show a octahedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify udinaite?+

Mohs hardness is 6. It typically shows a vitreous luster. The streak is white. Common colors include yellow, pale yellow.

Where is udinaite found?+

Notable localities include Tolbachik volcano, Kamchatka, Russia.

How much is udinaite worth?+

Typical asking prices fall in the range of $100-500 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like udinaite?+

Udinaite is most often confused with Spinel, Magnesioferrite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with udinaite?+

Udinaite commonly co-occurs with Tenorite, Hematite, Langbeinite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does udinaite form in?+

Udinaite typically forms in volcanic fumaroles. Working float back to the host body is the standard way to chase a fresh occurrence.

What is udinaite used for?+

Udinaite is used in collector.

Find udinaite on the map

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