Garronite-Ca is a member of the zeolite group found primarily in the vesicles of basaltic rocks. Collectors look for its distinctive white or colorless radiating aggregates which are often found alongside other zeolites like chabazite or phillipsite.

Hardness

4.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareZeolite Group family

Garronite-Ca

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

Is this garronite-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 garronite-ca with a known reference. Garronite-Ca sits at Mohs 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. Garronite-Ca leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Garronite-Ca typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, yellowish, pinkish.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: pseudotetragonal crystals, radiating aggregates, massive.

Often confused with

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

Often found alongside garronite-ca

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

All properties

Chemical formula: NaCa₂₅Al₅₂Si₁₃₂O₃₆₈·nH₂O
Mohs hardness: 4.5
Density: 2.12-2.14 g/cm³
Colors: White Colorless Yellowish Pinkish
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Pseudotetragonal Crystals, Radiating Aggregates, Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Amygdaloidal Basalt Cavities
Typical price: $20-150 depending on specimen size and quality

Where rockhounds find garronite-ca

Classic worldwide localities

Garron Plateau, Northern Ireland
Skye, Scotland
Iceland
Faeroe Islands
Melbourne, Victoria, Australia

Field-hunting tip

Look in amygdaloidal basalt cavities country — that is the host setting where garronite-ca typically forms. If you start seeing chabazite, thomsonite, phillipsite in float, you are in the right ground. Field specimens usually show a pseudotetragonal crystals, radiating aggregates, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify garronite-ca?+

Mohs hardness is 4.5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, yellowish, pinkish.

Where is garronite-ca found?+

Notable localities include Garron Plateau, Northern Ireland; Skye, Scotland; Iceland; Faeroe Islands; Melbourne, Victoria, Australia.

How much is garronite-ca worth?+

Typical asking prices fall in the range of $20-150 depending on specimen size and quality. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like garronite-ca?+

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

What minerals are found with garronite-ca?+

Garronite-Ca commonly co-occurs with Chabazite, Thomsonite, Phillipsite, Calcite, Analcime. Spotting any of these in float or country rock is a useful trip signal.

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

Garronite-Ca typically forms in amygdaloidal basalt cavities. Working float back to the host body is the standard way to chase a fresh occurrence.

What is garronite-ca used for?+

Garronite-Ca is used in collector.

Find garronite-ca on the map

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