Umbozerite is a very rare silicate mineral found in the alkaline rock complexes of the Kola Peninsula. It is highly valued by mineral collectors for its unique chemistry and radioactivity, often appearing as small, dull-brown granular masses within pegmatites.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent to transparent

mineralrareEudialyte Group family

Umbozerite

Hardness: ~5
Luster: Vitreous
Streak: White
Transparency: Translucent to transparent

Is this umbozerite?

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 umbozerite with a known reference. Umbozerite sits at Mohs ~5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: bottle green, greenish brown.
5
Look at form & habit
Crystal system: amorphous. Typical habit: metamict, pseudo tetragonal.

Often confused with

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

Often found alongside umbozerite

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

All properties

Chemical formula: Na₃Sr₄Th(Si₂O₇)₂(OH)₂·nH₂O
Mohs hardness: ~5
Density: 3.60 g/cm³
Colors: Bottle greenGreenish brown
Streak: White
Luster: Vitreous
Transparency: Translucent to transparent
Crystal system: Amorphous
Crystal habit: Metamict, pseudo tetragonal
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In pneumatolytic-hydrothermal veins cutting alkalic rocks in the upper part of a differentiated alkalic massif

Where rockhounds find umbozerite

Classic worldwide localities

Found on Mts. Karnasurt and Punkaruaiv, near Lake Umba, Lovozero massif, Kola Peninsula, Russia

Field-hunting tip

Where it forms: In pneumatolytic-hydrothermal veins cutting alkalic rocks in the upper part of a differentiated alkalic massif. If you start seeing ussingite, sphalerite, belovite in float, you are in the right ground. Typical habit: metamict, pseudo tetragonal. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify umbozerite?+

Mohs hardness is ~5. Luster: vitreous. The streak is white. Common colors include bottle green, greenish brown.

Where is umbozerite found?+

Notable localities include Found on Mts. Karnasurt and Punkaruaiv, near Lake Umba, Lovozero massif, Kola Peninsula, Russia.

Is umbozerite safe to handle?+

Umbozerite contains uranium or thorium and calls for real care. Contains thorium, which is radioactive. Handle with care, store in a dedicated container, and wash hands thoroughly after handling.

What rocks look like umbozerite?+

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

What minerals are found with umbozerite?+

Umbozerite commonly co-occurs with Ussingite, Sphalerite, Belovite, Manganoan pectolite, Lorenzenite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does umbozerite form in?+

Where it forms: In pneumatolytic-hydrothermal veins cutting alkalic rocks in the upper part of a differentiated alkalic massif. Working float back to the host body is the standard way to chase a fresh occurrence.

What is umbozerite used for?+

Umbozerite is used in collector.

Find umbozerite on the map

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