Ekaterinite is a rare calcium borate halide mineral found primarily in the Korshunovskoye iron deposit in Siberia. It typically forms small, clear, tetragonal prismatic crystals in cavities within iron ore deposits.

Hardness

1-1.5

Mohs

Luster

Pearly

Streak

White

Transparency

Transparent to translucent

mineralrareBorate Group family

Ekaterinite

Hardness: 1-1.5
Luster: Pearly
Streak: White
Transparency: Transparent to translucent

Is this ekaterinite?

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 ekaterinite with a known reference. Ekaterinite sits at Mohs 1-1.5, 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: pearly.
4
Match the color range
Compare against the expected color range: pearl white, pink.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: prismatic crystals.

Often confused with

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

mineral

Boracite

Mohs 7-7.5

How to tell apart: Boracite is the harder of the two (Mohs 7-7.5 vs. 1-1.5); luster reads pearly on Ekaterinite and vitreous to adamantine on Boracite.

Compare →

Often found alongside ekaterinite

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

All properties

Chemical formula: Ca₂B₄O₇Cl₂·2H₂O
Mohs hardness: 1-1.5
Density: 2.440 g/cm³
Colors: Pearl white Pink
Streak: White
Luster: Pearly
Transparency: Transparent to translucent
Crystal system: Hexagonal
Crystal habit: Prismatic crystals
Cleavage: On {0001}, distinct, foliated
Rarity: Rare
Uses: Collector
Host rock: In calcite and calcite–anhydrite veins associated with a mineralized skarn

Where rockhounds find ekaterinite

Classic worldwide localities

From drill cores in the Korshunovskoye ironboron skarn deposit, Irkutsk district, Siberia, Russia (type locality)

Field-hunting tip

Where it forms: In calcite and calcite–anhydrite veins associated with a mineralized skarn. If you start seeing halite, calcite, szaibélyite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ekaterinite?+

Mohs hardness is 1-1.5. Luster: pearly. The streak is white. Common colors include pearl white, pink.

Where is ekaterinite found?+

Notable localities include From drill cores in the Korshunovskoye ironboron skarn deposit, Irkutsk district, Siberia, Russia (type locality).

What rocks look like ekaterinite?+

Ekaterinite is most often confused with Boracite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ekaterinite?+

Ekaterinite commonly co-occurs with Halite, Calcite, Szaibélyite, Korshunovskite, Shabynite, Iowaite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ekaterinite form in?+

Where it forms: In calcite and calcite–anhydrite veins associated with a mineralized skarn. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ekaterinite used for?+

Ekaterinite is used in collector.

Find ekaterinite on the map

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