Willhendersonite is a rare potassium-calcium zeolite typically found in the vesicles of basaltic rocks. It is visually very similar to chabazite and often requires X-ray diffraction or chemical analysis for positive identification.
Is this willhendersonite?
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 willhendersonite with a known reference. Willhendersonite sits at Mohs ~3, 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.
- 5Look at form & habitCrystal system: triclinic. Typical habit: pseudo-rhombohedral crystals, often as complex intergrowths.
Often confused with
Willhendersonite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside willhendersonite
Minerals reported to co-occur with willhendersonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Ca₂Al₆Si₆O₂₄·10H₂O
- Mohs hardness
- ~3
- Density
- 2.10-2.18 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Pseudo-rhombohedral crystals, often as complex intergrowths
- Cleavage
- Perfect on {100}, {010}, and {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed by low-temperature hydrothermal alteration of potassic basaltic lavas (San Venanzo quarry, Italy)
Where rockhounds find willhendersonite
Classic worldwide localities
- Vispi quarry, near San Venanzo, Umbria, Italy
- Ettringer Bellerberg volcano, near Mayen, Eifel district, Germany
- Stradnerkogel, near Wilhelmsdorf, Styria, Austria
Field-hunting tip
Where it forms: A secondary mineral formed by low-temperature hydrothermal alteration of potassic basaltic lavas (San Venanzo quarry, Italy). If you start seeing phillipsite, thomsonite, apophyllite in float, you are in the right ground. Typical habit: pseudo-rhombohedral crystals, often as complex intergrowths. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify willhendersonite?+
Where is willhendersonite found?+
What rocks look like willhendersonite?+
What minerals are found with willhendersonite?+
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Find willhendersonite on the map
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