Kozoite-(La) is an extremely rare rare-earth carbonate mineral typically found as small, delicate acicular crystals or radiating fans. It was first described from Japan and is highly prized by systematic mineral collectors for its complexity and scarcity in the alkalic rock environments where it forms.

Hardness

4-4.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareAncylite Group family

Kozoite-(La)

Hardness: 4-4.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this kozoite-(la)?

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 kozoite-(la) with a known reference. Kozoite-(La) 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.
4
Match the color range
Compare against the expected color range: white, pale pinkish purple.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: spherical.

Often confused with

Kozoite-(La) vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside kozoite-(la)

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

All properties

Chemical formula: LaCO₃(OH)
Mohs hardness: 4-4.5
Density: 4.16 g/cm³
Colors: WhitePale pinkish purple
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Spherical
Rarity: Rare
Uses: Collector
Host rock: In cavities in an alkali olivine basalt lava flow

Where rockhounds find kozoite-(la)

Classic worldwide localities

Mitsukoshi, Hizen-cho, Saga Prefecture, Japan

Field-hunting tip

Where it forms: In cavities in an alkali olivine basalt lava flow. If you start seeing kozoite-, lanthanite-, kimuraite- in float, you are in the right ground. Typical habit: spherical. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kozoite-(la)?+

Mohs hardness is 4-4.5. Luster: vitreous. The streak is white. Common colors include white, pale pinkish purple.

Where is kozoite-(la) found?+

Notable localities include Mitsukoshi, Hizen-cho, Saga Prefecture, Japan.

What rocks look like kozoite-(la)?+

Kozoite-(La) is most often confused with Ancylite-(Ce), Kozoite-(Nd). A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with kozoite-(la)?+

Kozoite-(La) commonly co-occurs with Kozoite-, Lanthanite-, Kimuraite-, Lokkaite-, Calcite, Aragonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kozoite-(la) form in?+

Where it forms: In cavities in an alkali olivine basalt lava flow. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kozoite-(la) used for?+

Kozoite-(La) is used in collector.

Find kozoite-(la) on the map

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