Faujasite-Mg is a rare member of the zeolite group, forming as small, distinct octahedral crystals within volcanic rocks. Collectors prize it for its unique, highly ordered pore structure, though it is often difficult to distinguish from other members of the faujasite series without chemical analysis. It is most commonly found in basaltic vesicles associated with other secondary zeolite minerals.
Is this faujasite-mg?
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 faujasite-mg with a known reference. Faujasite-Mg sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: crystalline.
Often confused with
Faujasite-Mg vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside faujasite-mg
Minerals reported to co-occur with faujasite-mg. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Ca,Na₂,K₂)₃.₅[Al₇Si₁₇O₄₈]·32H₂O
- Mohs hardness
- 5
- Density
- 1.923-1.94 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Crystalline
- Cleavage
- Perfect on {111}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Usually occurs in basaltic volcanics, metapyroxenite, also with augite in limburgite
Where rockhounds find faujasite-mg
Classic worldwide localities
- Sasback in the Kaiserstuhl, Baden, Germany (type locality)
Field-hunting tip
Where it forms: Usually occurs in basaltic volcanics, metapyroxenite, also with augite in limburgite. If you start seeing phillipsite, chabazite, calcite in float, you are in the right ground. Typical habit: crystalline. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify faujasite-mg?+
Where is faujasite-mg found?+
What rocks look like faujasite-mg?+
What minerals are found with faujasite-mg?+
What kind of rock does faujasite-mg form in?+
What is faujasite-mg used for?+
Find faujasite-mg on the map
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