Chayesite is a rare member of the milarite group, typically occurring as small, honey-yellow prismatic crystals. It is most prominently found within alkaline igneous complexes such as those on the Kola Peninsula, where it forms in association with sodium-rich minerals.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareMilarite Group family

Chayesite

Hardness: 6
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this chayesite?

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 chayesite with a known reference. Chayesite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Chayesite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Chayesite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-brown.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: prismatic crystals.

Often confused with

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

Often found alongside chayesite

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

All properties

Chemical formula: KMg₄Si₁₂O₃₀
Mohs hardness: 6
Density: 2.73 g/cm³
Colors: Yellow Yellow-brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $50-300 per specimen

Where rockhounds find chayesite

Classic worldwide localities

Kola Peninsula, Russia

Field-hunting tip

Look in alkaline igneous rocks country — that is the host setting where chayesite typically forms. If you start seeing arfvedsonite, aegirine, microcline in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chayesite?+

Mohs hardness is 6. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellow-brown.

Where is chayesite found?+

Notable localities include Kola Peninsula, Russia.

How much is chayesite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like chayesite?+

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

What minerals are found with chayesite?+

Chayesite commonly co-occurs with Arfvedsonite, Aegirine, Microcline, Nepheline. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chayesite form in?+

Chayesite typically forms in alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is chayesite used for?+

Chayesite is used in collector.

Find chayesite on the map

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