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, 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.