Aleksandrovite is an extremely rare phyllosilicate mineral discovered in the Sakha Republic of Russia. It typically occurs as small tabular crystals within contact-metamorphosed limestone xenoliths. Due to its scarcity, it is almost exclusively found in advanced research collections.

Hardness

4-4.5

Mohs

Luster

Vitreous, pearly on cleavage surfaces

Streak

White

Transparency

Transparent

mineralrare

Aleksandrovite

Hardness: 4-4.5
Luster: Vitreous, pearly on cleavage surfaces
Streak: White
Transparency: Transparent

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Is this aleksandrovite?

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 aleksandrovite with a known reference. Aleksandrovite 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, pearly on cleavage surfaces.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals.

Often confused with

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

mineral

Quartz

Mohs 7

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

How to tell apart: Aleksandrovite is noticeably harder (Mohs 4-4.5 vs. 3).

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Often found alongside aleksandrovite

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

All properties

Chemical formula: KCa₇Sn₂Li₃Si₁₂O₃₆F₂
Mohs hardness: 4-4.5
Density: 3.05 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous, pearly on cleavage surfaces
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular crystals
Cleavage: Perfect on {001}
Rarity: Rare
Uses: Collector
Host rock: In a zoned microcline-calcite vein with aegirine-hedenbergite, quartz, and albite in a glacial moraine boulder

Where rockhounds find aleksandrovite

Classic worldwide localities

Darai-Pioz glacier, at the junction of the Turkestan, Zeravshan, and Alay Mountain Ranges, Tajikistan

Field-hunting tip

Where it forms: In a zoned microcline-calcite vein with aegirine-hedenbergite, quartz, and albite in a glacial moraine boulder. If you start seeing miserite, baratovite, katayamalite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify aleksandrovite?+

Mohs hardness is 4-4.5. Luster: vitreous, pearly on cleavage surfaces. The streak is white. Common colors include colorless.

Where is aleksandrovite found?+

Notable localities include Darai-Pioz glacier, at the junction of the Turkestan, Zeravshan, and Alay Mountain Ranges, Tajikistan.

What rocks look like aleksandrovite?+

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

What minerals are found with aleksandrovite?+

Aleksandrovite commonly co-occurs with Miserite, Baratovite, Katayamalite, Fluorite, Sn-titanite, Bazirite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does aleksandrovite form in?+

Where it forms: In a zoned microcline-calcite vein with aegirine-hedenbergite, quartz, and albite in a glacial moraine boulder. Working float back to the host body is the standard way to chase a fresh occurrence.

What is aleksandrovite used for?+

Aleksandrovite is used in collector.

Find aleksandrovite on the map

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