Gmelinite-Na is a member of the zeolite group typically found as distinctive rhombohedral crystals lining cavities in basalt. Collectors should look for its characteristic pseudo-hexagonal shape and frequent twinning, often accompanied by other zeolite minerals in volcanic environments.
Is this gmelinite-na?
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 gmelinite-na with a known reference. Gmelinite-Na sits at Mohs 4.5, 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, reddish white, pink, greenish white, flesh red.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: crystalline, druse.
Often confused with
Gmelinite-Na vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside gmelinite-na
Minerals reported to co-occur with gmelinite-na. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₄(Si₈Al₄)O₂₄·11H₂O
- Mohs hardness
- 4.5
- Density
- 2.02-2.17 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent, opaque
- Crystal system
- Hexagonal
- Crystal habit
- Crystalline, druse
- Cleavage
- {10*0}, distinct; parting on {00*1}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Formed from sodium-rich fluids, in basalts and related igneous rocks, also pegmatites
Where rockhounds find gmelinite-na
Classic worldwide localities
- Bergen Hill, Hudson Co., and Great Notch, Paterson, and Prospect Park, Passaic Co., New Jersey, USA
- Springfield, Lane Co., Oregon, USA
- Montecchio Maggiore, Vicenza, Italy
- Glenarm, in Co. Antrim, Ireland
- Isle of Skye, Scotland
- Pyrgos, Cyprus
Field-hunting tip
Where it forms: Formed from sodium-rich fluids, in basalts and related igneous rocks, also pegmatites. If you start seeing zeolites, calcite, aragonite in float, you are in the right ground. Typical habit: crystalline, druse. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gmelinite-na?+
Where is gmelinite-na found?+
What rocks look like gmelinite-na?+
What minerals are found with gmelinite-na?+
What kind of rock does gmelinite-na form in?+
What is gmelinite-na used for?+
Find gmelinite-na on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
