Clinoptilolite-Ca is a common member of the zeolite group, typically forming within volcanic tuffs where volcanic glass has altered in saline-alkaline lakes. It is frequently found as white or colorless tabular crystals in basalt cavities or as extensive massive deposits, and it is highly valued industrially for its ion-exchange properties.

Hardness

3.5-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralcommonHeulandite Group family

Clinoptilolite-Ca

Hardness: 3.5-4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this clinoptilolite-ca?

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 clinoptilolite-ca with a known reference. Clinoptilolite-Ca sits at Mohs 3.5-4, 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, reddish white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: crystalline, tabular.

Often confused with

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

Often found alongside clinoptilolite-ca

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

All properties

Chemical formula: Ca₃(Si₃₀Al₆)O₇₂·20H₂O
Mohs hardness: 3.5-4
Density: 2.1-2.2 g/cm³
Colors: White Reddish white
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Crystalline, tabular
Cleavage: Perfect on {010}
Rarity: Common
Uses: Industrial, Collector
Host rock: Most commonly formed as a devitrification product of silicic volcanic glass from tuffs

Where rockhounds find clinoptilolite-ca

Classic worldwide localities

Kuruma Pass, Fukushima Prefecture, Japan (type locality)

Field-hunting tip

Where it forms: Most commonly formed as a devitrification product of silicic volcanic glass from tuffs. If you start seeing quartz, calcite, mordenite in float, you are in the right ground. Typical habit: crystalline, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify clinoptilolite-ca?+

Mohs hardness is 3.5-4. Luster: vitreous. The streak is white. Common colors include white, reddish white.

Where is clinoptilolite-ca found?+

Notable localities include Kuruma Pass, Fukushima Prefecture, Japan (type locality).

What rocks look like clinoptilolite-ca?+

Clinoptilolite-Ca is most often confused with Heulandite, Stilbite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with clinoptilolite-ca?+

Clinoptilolite-Ca commonly co-occurs with Quartz, Calcite, Mordenite, Chabazite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does clinoptilolite-ca form in?+

Where it forms: Most commonly formed as a devitrification product of silicic volcanic glass from tuffs. Working float back to the host body is the standard way to chase a fresh occurrence.

What is clinoptilolite-ca used for?+

Clinoptilolite-Ca is used in industrial, collector.

Find clinoptilolite-ca on the map

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