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

mineralrareEudialyte Group family

Umbozerite

Hardness: 4
Luster: Vitreous
Streak: White
Transparency: Translucent

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 4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Umbozerite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Umbozerite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: brown, yellow, orange.
5
Look at form & habit
Crystal system: trigonal. Typical habit: granular.

Often confused with

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

mineral

Eudialyte

Mohs 5-6

How to tell apart: Eudialyte is the harder of the two (Mohs 5-6 vs. 4).

How to tell apart: Kentbrooksite is the harder of the two (Mohs 5-6 vs. 4).

Compare →

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: 4
Density: 3.3 g/cm³
Colors: Brown Yellow Orange
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Granular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Pegmatites
Typical price: $50-200 per specimen

Where rockhounds find umbozerite

Classic worldwide localities

Umbozero Mine, Kola Peninsula, Russia

Field-hunting tip

Look in alkaline pegmatites country — that is the host setting where umbozerite typically forms. If you start seeing aegirine, nepheline, microcline in float, you are in the right ground. Field specimens usually show a granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify umbozerite?+

Mohs hardness is 4. It typically shows a vitreous luster. The streak is white. Common colors include brown, yellow, orange.

Where is umbozerite found?+

Notable localities include Umbozero Mine, Kola Peninsula, Russia.

How much is umbozerite worth?+

Typical asking prices fall in the range of $50-200 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is umbozerite safe to handle?+

This mineral is radioactive. Contains thorium, which is radioactive. Handle with care, store in a dedicated container, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

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 Aegirine, Nepheline, Microcline. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does umbozerite form in?+

Umbozerite typically forms in alkaline pegmatites. 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.