Merlinoite is a rare member of the zeolite group that typically occurs as small, clear, pseudo-cubic crystals within volcanic vesicles. It is chemically similar to phillipsite but is distinguished by its specific orthorhombic symmetry and diffraction patterns. It is highly sought after by micromount collectors due to its restricted occurrence in specific volcanic environments.
Is this merlinoite?
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 merlinoite with a known reference. Merlinoite 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, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, radial, spherical.
Often confused with
Merlinoite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside merlinoite
Minerals reported to co-occur with merlinoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₅Ca₂(Si₂₃Al₉)O₆₄·24H₂O
- Mohs hardness
- 4.5
- Density
- 2.14-2.27 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, radial, spherical
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in veins and cavities of silica-undersaturated volcanic rocks (Cupaello, Italy); an alteration product of cataclastized pegmatitic rocks in a differentiated alkalic massif (Khibiny massif, Russia)
Where rockhounds find merlinoite
Classic worldwide localities
- Searles Lake, San Bernardino Co., California, USA
- Cupaello quarry, near Santa Rufina, and at Valle Beachella, Sacrofano, near Rome, Lazio, Italy
- Höwenegg quarry, Hegau, Baden-Württemberg, and in the Ortenberg quarry, Vogelsberg, Hesse, Germany
- Khibiny massif, Kola Peninsula, Russia
- Central Indian basin, Indian Ocean
Field-hunting tip
Where it forms: A secondary mineral in veins and cavities of silica-undersaturated volcanic rocks (Cupaello, Italy); an alteration product of cataclastized pegmatitic rocks in a differentiated alkalic massif (Khibiny massif, Russia). If you start seeing phillipsite, apophyllite, chabazite in float, you are in the right ground. Typical habit: fibrous, radial, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify merlinoite?+
Where is merlinoite found?+
What rocks look like merlinoite?+
What minerals are found with merlinoite?+
What kind of rock does merlinoite form in?+
What is merlinoite used for?+
Find merlinoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
