Uralborite is a rare calcium borate mineral primarily found within skarn deposits in contact metamorphic zones. It typically occurs in massive or granular forms and is most notable for its origin in the iron-rich skarn systems of the Ural Mountains.

Hardness

4-4.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareBorate Group family

Uralborite

Hardness: 4-4.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this uralborite?

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 uralborite with a known reference. Uralborite sits at Mohs 4-4.5, 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: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: granular to massive, occasionally as small prismatic crystals.

Often confused with

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

mineral

Danburite

Mohs 7-7.25

How to tell apart: Danburite is the harder of the two (Mohs 7-7.25 vs. 4-4.5).

Often found alongside uralborite

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

All properties

Chemical formula: CaB₂O₂(OH)₄
Mohs hardness: 4-4.5
Density: 2.58-2.60 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Granular to massive, occasionally as small prismatic crystals
Cleavage: Indistinct
Fluorescence: Violet under LW UV
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral in boron-rich iron-ore skarns (Novofrolovskoye deposit, Russia); in a vein cutting limestone (Fuka, Japan)

Where rockhounds find uralborite

Classic worldwide localities

Novofrolovskoye copper deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, and in the Solongo boron deposit, Buryatia, Russia
Found at Fuka, near Bicchu, Okayama Prefecture, Japan

Field-hunting tip

Where it forms: A rare secondary mineral in boron-rich iron-ore skarns (Novofrolovskoye deposit, Russia); in a vein cutting limestone (Fuka, Japan). If you start seeing andradite–grossular, magnetite, szaibélyite in float, you are in the right ground. Typical habit: granular to massive, occasionally as small prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify uralborite?+

Mohs hardness is 4-4.5. Luster: vitreous. The streak is white. Common colors include colorless.

Where is uralborite found?+

Notable localities include Novofrolovskoye copper deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, and in the Solongo boron deposit, Buryatia, Russia; Found at Fuka, near Bicchu, Okayama Prefecture, Japan.

What rocks look like uralborite?+

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

What minerals are found with uralborite?+

Uralborite commonly co-occurs with Andradite–grossular, Magnetite, Szaibélyite, Frolovite, Sibirskite, Borcarite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does uralborite form in?+

Where it forms: A rare secondary mineral in boron-rich iron-ore skarns (Novofrolovskoye deposit, Russia); in a vein cutting limestone (Fuka, Japan). Working float back to the host body is the standard way to chase a fresh occurrence.

What is uralborite used for?+

Uralborite is used in collector.

Find uralborite on the map

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