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 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Gmelinite-K leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Gmelinite-K typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellow, pink, red.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: rhombohedral crystals, sometimes pseudohexagonal tabular crystals.
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
- (K₂,Ca,Na₂)₄Al₈Si₁₆O₄₈·22H₂O
- Mohs hardness
- 4.5
- Density
- 2.05-2.15 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Rhombohedral Crystals, Sometimes Pseudohexagonal Tabular Crystals
- Cleavage
- Distinct On {1011}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Basaltic Volcanic Rocks and Vesicles
- Typical price
- $20-150 depending on specimen size and clarity
Where rockhounds find gmelinite-k
Classic worldwide localities
- Australia
- Italy
- Canada
- Russia
- USA
Field-hunting tip
Look in basaltic volcanic rocks and vesicles country — that is the host setting where gmelinite-k typically forms. If you start seeing chabazite, phillipsite, natrolite in float, you are in the right ground. Field specimens usually show a rhombohedral crystals, sometimes pseudohexagonal tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gmelinite-k?+
Where is gmelinite-k found?+
How much is gmelinite-k worth?+
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.
