Sibirskite is a rare calcium borate mineral typically found in metamorphosed carbonate rocks associated with skarn deposits. It usually occurs as small, white to colorless platy or fibrous crystalline aggregates. It is primarily a collector's mineral known from the Tayozhnoye iron ore deposit in the Sakha Republic of Russia.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrareLudwigite Group family

Sibirskite

Hardness: 3-4
Luster: Vitreous
Streak: White
Transparency: Semitransparent

Is this sibirskite?

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 sibirskite with a known reference. Sibirskite sits at Mohs 3-4, 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, dark gray.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy or fibrous aggregates.

Often confused with

Sibirskite 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. 3-4).

Often found alongside sibirskite

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

All properties

Chemical formula: CaHBO₃
Mohs hardness: 3-4
Density: 2.58 g/cm³
Colors: Colorless Dark gray
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Monoclinic
Crystal habit: Platy or fibrous aggregates
Cleavage: Good
Rarity: Rare
Uses: Collector, Research
Host rock: In veinlets and aggregates in skarns

Where rockhounds find sibirskite

Classic worldwide localities

Yuliya Svintsovaya Pb–Zn deposit, 20 km east-northeast of the Son railway station, Khakassia district, Siberia, Russia
Novofrolovskoye copper deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia
Chersk and Selenyakhsk Ridges, Transbaikal, Russia
Fuka, near Bicchu, Okayama Prefecture, Japan

Field-hunting tip

Where it forms: In veinlets and aggregates in skarns. If you start seeing calcite, chlorite, pyrite in float, you are in the right ground. Typical habit: platy or fibrous aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify sibirskite?+

Mohs hardness is 3-4. Luster: vitreous. The streak is white. Common colors include colorless, dark gray.

Where is sibirskite found?+

Notable localities include Yuliya Svintsovaya Pb–Zn deposit, 20 km east-northeast of the Son railway station, Khakassia district, Siberia, Russia; Novofrolovskoye copper deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia; Chersk and Selenyakhsk Ridges, Transbaikal, Russia; Fuka, near Bicchu, Okayama Prefecture, Japan.

What rocks look like sibirskite?+

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

What minerals are found with sibirskite?+

Sibirskite commonly co-occurs with Calcite, Chlorite, Pyrite, Garnet, Vesuvianite, Datolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does sibirskite form in?+

Where it forms: In veinlets and aggregates in skarns. Working float back to the host body is the standard way to chase a fresh occurrence.

What is sibirskite used for?+

Sibirskite is used in collector, research.

Find sibirskite on the map

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