Caryochroite is a rare phyllosilicate mineral typically found in the alkaline rock environments of the Kola Peninsula. It often occurs as small, brownish, platy crystals that resemble chlorite but can be distinguished through analytical testing of its unique sodium and strontium content.

Hardness

2.5

Mohs

Luster

Dull to waxy

Streak

Pale brownish yellow

Transparency

Opaque

mineralrare

Caryochroite

Hardness: 2.5
Luster: Dull to waxy
Streak: Pale brownish yellow
Transparency: Opaque

No image

Is this caryochroite?

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 caryochroite with a known reference. Caryochroite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale brownish yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: dull to waxy.
4
Match the color range
Compare against the expected color range: hazel brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: pseudomorphous, spherical.

Often found alongside caryochroite

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

All properties

Chemical formula: (Na,Sr)₃(Fe,Mg)₁₀Ti₂Si₁₂O₃₇(H₂O,O,OH)₁₇
Mohs hardness: 2.5
Density: 2.990 g/cm³
Colors: Hazel brown
Streak: Pale brownish yellow
Luster: Dull to waxy
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Pseudomorphous, spherical
Cleavage: Good on {001}
Rarity: Rare
Uses: Collector
Host rock: Product of the supergene alteration of an unidentified Fe2+ -rich protophase in cavities in the albite zone of a pegmatite

Where rockhounds find caryochroite

Classic worldwide localities

Umbozero mine, Alluaiv, Lovozero, Kola Peninsula, Russia (type locality)

Field-hunting tip

Where it forms: Product of the supergene alteration of an unidentified Fe2+ -rich protophase in cavities in the albite zone of a pegmatite. If you start seeing albite, elpidite, epididymite in float, you are in the right ground. Typical habit: pseudomorphous, spherical. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify caryochroite?+

Mohs hardness is 2.5. Luster: dull to waxy. The streak is pale brownish yellow. Common colors include hazel brown.

Where is caryochroite found?+

Notable localities include Umbozero mine, Alluaiv, Lovozero, Kola Peninsula, Russia (type locality).

What minerals are found with caryochroite?+

Caryochroite commonly co-occurs with Albite, Elpidite, Epididymite, Quartz, Natrolite, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does caryochroite form in?+

Where it forms: Product of the supergene alteration of an unidentified Fe2+ -rich protophase in cavities in the albite zone of a pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is caryochroite used for?+

Caryochroite is used in collector.

Find caryochroite on the map

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