Sergeevite is a rare hydrated calcium magnesium carbonate mineral typically found in sedimentary evaporite environments. It usually appears as fine-grained, pearly white crusts or platy aggregates, making it difficult to distinguish from common carbonates without chemical testing.

Hardness

2-3

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrare

Sergeevite

Hardness: 2-3
Luster: Pearly
Streak: White
Transparency: Translucent

Is this sergeevite?

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 sergeevite with a known reference. Sergeevite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Sergeevite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Sergeevite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale yellow.
5
Look at form & habit
Crystal system: trigonal. Typical habit: platy crystals, aggregates, crusts.

Often confused with

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

mineral

Calcite

Mohs 3

How to tell apart: Luster reads pearly on Sergeevite and vitreous on Calcite.

How to tell apart: Luster reads pearly on Sergeevite and vitreous on Dolomite.

Often found alongside sergeevite

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

All properties

Chemical formula: Ca₂Mg(CO₃)₃(HCO₃)₂·3H₂O
Mohs hardness: 2-3
Density: 2.1-2.2 g/cm³
Colors: White Colorless Pale Yellow
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Platy Crystals, Aggregates, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Evaporite Deposits
Typical price: $20-100 per specimen

Where rockhounds find sergeevite

Classic worldwide localities

Khanda-Gyl deposit, Russia
Khibiny Massif, Russia

Field-hunting tip

Look in hydrothermal veins in evaporite deposits country — that is the host setting where sergeevite typically forms. If you start seeing calcite, dolomite, hydromagnesite in float, you are in the right ground. Field specimens usually show a platy crystals, aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify sergeevite?+

Mohs hardness is 2-3. It typically shows a pearly luster. The streak is white. Common colors include white, colorless, pale yellow.

Where is sergeevite found?+

Notable localities include Khanda-Gyl deposit, Russia; Khibiny Massif, Russia.

How much is sergeevite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like sergeevite?+

Sergeevite is most often confused with Calcite, Dolomite, Hydromagnesite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with sergeevite?+

Sergeevite commonly co-occurs with Calcite, Dolomite, Hydromagnesite, Magnesite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does sergeevite form in?+

Sergeevite typically forms in hydrothermal veins in evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is sergeevite used for?+

Sergeevite is used in collector.

Find sergeevite on the map

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