Gmelinite-K is a rare zeolite mineral occurring primarily in the vesicles of basaltic rocks. Collectors typically look for its characteristic pseudohexagonal, rhombohedral crystal shapes that form in drusy coatings or individual clusters.
Is this gmelinite-k?
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-k with a known reference. Gmelinite-K sits at Mohs 4, 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: colorless, brownish white.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: aggregates, granular, radial.
Often confused with
Gmelinite-K vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside gmelinite-k
Minerals reported to co-occur with gmelinite-k. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₄(Si₈Al₄)O₂₄·11H₂O
- Mohs hardness
- 4
- Density
- 2.00 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Aggregates, granular, radial
- Cleavage
- {10*0}, distinct; parting on {00*1}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As drusy aggregates in cavities within brecciated pegmatite
Where rockhounds find gmelinite-k
Classic worldwide localities
- Mount Alluaiv, Lovozero alkaline massif, Kola Peninsula, Russia (type locality)
- Fara Vicentina, Vicenza, Italy
Field-hunting tip
Where it forms: As drusy aggregates in cavities within brecciated pegmatite. If you start seeing k-feldspar, nepheline, sodalite in float, you are in the right ground. Typical habit: aggregates, granular, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gmelinite-k?+
Where is gmelinite-k found?+
What rocks look like gmelinite-k?+
What minerals are found with gmelinite-k?+
What kind of rock does gmelinite-k form in?+
What is gmelinite-k used for?+
Find gmelinite-k on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
