Kuzelite is a rare layered double hydroxide mineral typically found in environments associated with the hydration of industrial waste like blast furnace slag or concrete. Collectors should look for delicate, white to colorless hexagonal plates or radiating rosettes in cavities of anthropogenic materials. It is a scientifically significant mineral for understanding mineral crystallization in artificial geological settings.

Hardness

1-2

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareHydrotalcite Supergroup family

Kuzelite

Hardness: 1-2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this kuzelite?

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 kuzelite with a known reference. Kuzelite sits at Mohs 1-2, 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.
5
Look at form & habit
Crystal system: trigonal. Typical habit: microscopic crystals, platy.

Often confused with

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

How to tell apart: Hydrocalumite is the harder of the two (Mohs 3 vs. 1-2).

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Often found alongside kuzelite

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

All properties

Chemical formula: Ca₄Al₂(OH)₁₂(SO₄)·6H₂O
Mohs hardness: 1-2
Density: 1.99 g/cm³
Colors: White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Microscopic crystals, platy
Cleavage: On {0001}, perfect
Rarity: Rare
Uses: Collector
Host rock: A rare mineral in carbonaceous xenoliths in basalt, formed above 100°C by decomposition of ettringite

Where rockhounds find kuzelite

Classic worldwide localities

Zeilberg quarry, Maroldsweisach, Bavaria, and at the Bellerberg volcano, two km north of Mayen, Eifel district, Germany

Field-hunting tip

Where it forms: A rare mineral in carbonaceous xenoliths in basalt, formed above 100°C by decomposition of ettringite. If you start seeing ettringite, afwillite, natrolite in float, you are in the right ground. Typical habit: microscopic crystals, platy. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kuzelite?+

Mohs hardness is 1-2. Luster: vitreous. The streak is white. Common colors include white.

Where is kuzelite found?+

Notable localities include Zeilberg quarry, Maroldsweisach, Bavaria, and at the Bellerberg volcano, two km north of Mayen, Eifel district, Germany.

What rocks look like kuzelite?+

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

What minerals are found with kuzelite?+

Kuzelite commonly co-occurs with Ettringite, Afwillite, Natrolite, Calcite, Torbermorite, Gyrolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kuzelite form in?+

Where it forms: A rare mineral in carbonaceous xenoliths in basalt, formed above 100°C by decomposition of ettringite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kuzelite used for?+

Kuzelite is used in collector.

Find kuzelite on the map

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