Wairakite is a rare calcium-rich member of the zeolite group that is chemically and structurally similar to analcime. It is typically found as a secondary mineral in geothermal fields, occurring within altered volcanic rocks or deposited from hot springs. Collectors value it for its characteristic trapezohedral crystal habit, which often mimics the appearance of analcime.

Hardness

5.5-6

Mohs

Luster

Vitreous to nearly dull

Streak

White

Transparency

Transparent to translucent

mineraluncommonZeolite Group family

Wairakite

Hardness: 5.5-6
Luster: Vitreous to nearly dull
Streak: White
Transparency: Transparent to translucent

Is this wairakite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch wairakite with a known reference. Wairakite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to nearly dull.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: trapezohedral crystals, granular, massive.

Often confused with

Wairakite vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside wairakite

Minerals reported to co-occur with wairakite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CaAl₂Si₄O₁₂·2H₂O
Mohs hardness: 5.5-6
Density: 2.26 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous to nearly dull
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Trapezohedral crystals, granular, massive
Cleavage: Two sets of possible partings intersecting at 90°
Rarity: Uncommon
Uses: Collector
Host rock: In pores and cavities in rocks in geothermal areas, deposited from hydrothermal fluids; may replace feldspar

Where rockhounds find wairakite

Classic worldwide localities

Geysers, Sonoma Co., and near Rosamond, Kern Co., California, USA
Yellowstone National Park, Wyoming, USA
Mt. Rainier National Park, Pierce Co., Washington, USA
North Island, at Wairakei, about six km north-northeast of Lake Taupo, and in the Tui mine, Te Aroha, Auckland, New Zealand
St. Thomas and St. Croix, American Virgin Islands
Buttle Lake area, Vancouver Island, British Columbia, Canada

Field-hunting tip

Where it forms: In pores and cavities in rocks in geothermal areas, deposited from hydrothermal fluids; may replace feldspar. If you start seeing andesine, epidote, clinozoisite in float, you are in the right ground. Typical habit: trapezohedral crystals, granular, massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify wairakite?+

Mohs hardness is 5.5-6. Luster: vitreous to nearly dull. The streak is white. Common colors include white, colorless.

Where is wairakite found?+

Notable localities include Geysers, Sonoma Co., and near Rosamond, Kern Co., California, USA; Yellowstone National Park, Wyoming, USA; Mt. Rainier National Park, Pierce Co., Washington, USA; North Island, at Wairakei, about six km north-northeast of Lake Taupo, and in the Tui mine, Te Aroha, Auckland, New Zealand; St. Thomas and St. Croix, American Virgin Islands.

What rocks look like wairakite?+

Wairakite is most often confused with Analcime, Leucite, Pollucite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with wairakite?+

Wairakite commonly co-occurs with Andesine, Epidote, Clinozoisite, Prehnite, Calcite, Aragonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does wairakite form in?+

Where it forms: In pores and cavities in rocks in geothermal areas, deposited from hydrothermal fluids; may replace feldspar. Working float back to the host body is the standard way to chase a fresh occurrence.

What is wairakite used for?+

Wairakite is used in collector.

Find wairakite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.