Erionite-K is a member of the zeolite group that typically forms as delicate, hair-like fibers or woolly mats in volcanic environments. Collectors should be aware of its asbestiform nature, which requires strict safety protocols to prevent inhalation of hazardous fibers during specimen management.
Is this erionite-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 erionite-k with a known reference. Erionite-K sits at Mohs 3.5-4, 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 to silky.
- 4Match the color rangeCompare against the expected color range: white, green, gray, orange.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular.
Often confused with
Erionite-K vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside erionite-k
Minerals reported to co-occur with erionite-k. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₁₀(Si₂₆Al₁₀O₇₂)·30H₂O
- Mohs hardness
- 3.5-4
- Density
- 2.08 g/cm³
- Streak
- White
- Luster
- Vitreous to silky
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular
- Cleavage
- Poor prismatic
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- In basalts; in altered rhyolitic tuffs and lake-bed sediments formed by alteration of vitric ash fallen into the lakes
Where rockhounds find erionite-k
Classic worldwide localities
- Tecopa, Inyo Co., California, USA
- Pine Valley, Eureka Co., Eastgate, Churchill Co., Jersey Valley, Pershing Co., and Reese River, Lander Co., Nevada, USA
- Cape Lookout, Tillamook Co., Agate Beach, Lincoln Co., and Durkee, Baker Co., Oregon, USA
- Parkgate quarry, Templepatrick, Co. Antrim, Ireland
- Hvalstod and in the Berufjord area, Iceland
- Moeraki, Otago, South Island, New Zealand
Field-hunting tip
Where it forms: In basalts; in altered rhyolitic tuffs and lake-bed sediments formed by alteration of vitric ash fallen into the lakes. If you start seeing zeolites, opal, quartz in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify erionite-k?+
Where is erionite-k found?+
Is erionite-k safe to handle?+
What rocks look like erionite-k?+
What minerals are found with erionite-k?+
What kind of rock does erionite-k form in?+
What is erionite-k used for?+
Find erionite-k on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
