Cymrite is a rare barium phyllosilicate mineral that often forms thin, pearly, micaceous plates. It is typically found in low-grade metamorphic rocks and hydrothermal deposits associated with barite-rich environments. Collectors should look for its distinctive pearly luster and perfect basal cleavage, which makes it look remarkably like mica.

Hardness

2-3

Mohs

Luster

Vitreous to satiny

Streak

White

Transparency

Translucent

mineralrare

Cymrite

Hardness: 2-3
Luster: Vitreous to satiny
Streak: White
Transparency: Translucent

Is this cymrite?

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 cymrite with a known reference. Cymrite 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. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to satiny.
4
Match the color range
Compare against the expected color range: brown, colorless, green, dark green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy.

Often confused with

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

Often found alongside cymrite

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

All properties

Chemical formula: BaAl₂Si₂ (O,OH)₈·H₂O
Mohs hardness: 2-3
Density: 3.413 g/cm³
Colors: Brown Colorless Green Dark green
Streak: White
Luster: Vitreous to satiny
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy
Cleavage: Perfect on {001}, imperfect on {110}
Rarity: Rare
Uses: Collector
Host rock: In veinlets cutting hydrothermal manganese silicate ore (Benallt mine, Wales); in a copper-bearing deposit in dolostones and siderites (Ruby Creek, Alaska, USA)

Where rockhounds find cymrite

Classic worldwide localities

Ruby Creek, Brooks Range, Alaska, and near Pacheco Pass, San Benito Co., California, USA
Benallt mine, Rhiw, Lleyn Peninsula, Wales
Långban, Värmland, Sweden
Andros Island, Cyclades Islands, Greece
Lianyuan-Shaoyang area, Hunan Province, China
Shiramaru mine, Tokyo Prefecture, Japan

Field-hunting tip

Where it forms: In veinlets cutting hydrothermal manganese silicate ore (Benallt mine, Wales); in a copper-bearing deposit in dolostones and siderites (Ruby Creek, Alaska, USA). If you start seeing ganophyllite, calcite, albite in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cymrite?+

Mohs hardness is 2-3. Luster: vitreous to satiny. The streak is white. Common colors include brown, colorless, green, dark green.

Where is cymrite found?+

Notable localities include Ruby Creek, Brooks Range, Alaska, and near Pacheco Pass, San Benito Co., California, USA; Benallt mine, Rhiw, Lleyn Peninsula, Wales; Långban, Värmland, Sweden; Andros Island, Cyclades Islands, Greece; Lianyuan-Shaoyang area, Hunan Province, China.

What rocks look like cymrite?+

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

What minerals are found with cymrite?+

Cymrite commonly co-occurs with Ganophyllite, Calcite, Albite, Lawsonite, Hyalotekite, Banalsite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cymrite form in?+

Where it forms: In veinlets cutting hydrothermal manganese silicate ore (Benallt mine, Wales); in a copper-bearing deposit in dolostones and siderites (Ruby Creek, Alaska, USA). Working float back to the host body is the standard way to chase a fresh occurrence.

What is cymrite used for?+

Cymrite is used in collector.

Find cymrite on the map

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