Phillipsite-Ca is a common zeolite mineral recognized for its distinctive complex penetration twinning which often forms cross-shaped crystals. It is typically found lining amygdaloidal cavities in volcanic rocks or as authigenic crystals in marine deposits. Collectors should look for its classic cruciform habit, usually associated with other zeolites and calcite.
Is this phillipsite-ca?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch phillipsite-ca with a known reference. Phillipsite-Ca sits at Mohs 4-4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Phillipsite-Ca leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Phillipsite-Ca typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellow, reddish, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: complex cruciform penetration twins, radiating aggregates.
Often confused with
Phillipsite-Ca vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside phillipsite-ca
Minerals reported to co-occur with phillipsite-ca. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na₂,K₂)₃(Si₁₀Al₆)O₃₂·12H₂O
- Mohs hardness
- 4-4.5
- Density
- 2.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Complex Cruciform Penetration Twins, Radiating Aggregates
- Cleavage
- Distinct On {100} and {010}
- Rarity
- Common
- Uses
- Collector, Scientific Research
- Host rock
- Cavities in Basaltic Volcanic Rocks, Deep-sea Sediments
- Typical price
- $10-60 per specimen
Where rockhounds find phillipsite-ca
Classic worldwide localities
- Vesuvius, Italy
- Cape Vogel, Papua New Guinea
- Iceland
- Hawaii, USA
- Germany
Field-hunting tip
Look in cavities in basaltic volcanic rocks, deep-sea sediments country — that is the host setting where phillipsite-ca typically forms. If you start seeing calcite, analcime, natrolite in float, you are in the right ground. Field specimens usually show a complex cruciform penetration twins, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify phillipsite-ca?+
Where is phillipsite-ca found?+
How much is phillipsite-ca worth?+
What rocks look like phillipsite-ca?+
What minerals are found with phillipsite-ca?+
What kind of rock does phillipsite-ca form in?+
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Find phillipsite-ca on the map
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