Iowaite is a rare layered double hydroxide mineral typically found as green to blue-green platy aggregates in serpentinized rocks. It is highly unstable when exposed to air and can dehydrate or alter rapidly, making it a challenging but rewarding find for mineral collectors.

Hardness

1.5-2

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareHydrotalcite Supergroup family

Iowaite

Hardness: 1.5-2
Luster: Pearly
Streak: White
Transparency: Translucent

Is this iowaite?

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 iowaite with a known reference. Iowaite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Iowaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Iowaite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: green, blue-green.
5
Look at form & habit
Crystal system: trigonal. Typical habit: platy crystals, massive, or as vein fillings.

Often confused with

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

Often found alongside iowaite

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

All properties

Chemical formula: Mg₄Fe³⁺(OH)₈Cl·4H₂O
Mohs hardness: 1.5-2
Density: 2.1-2.2 g/cm³
Colors: Green Blue-green
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Platy Crystals, Massive, Or as Vein Fillings
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Serpentinized Ultramafic Rocks
Typical price: $20-100 per specimen

Where rockhounds find iowaite

Classic worldwide localities

Iowa, USA
Tasmania, Australia
Quebec, Canada

Field-hunting tip

Look in serpentinized ultramafic rocks country, the host setting where iowaite typically forms. If you start seeing serpentine, magnetite, dolomite in float, you are in the right ground. Field specimens usually show a platy crystals, massive, or as vein fillings habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify iowaite?+

Mohs hardness is 1.5-2. It typically shows a pearly luster. The streak is white. Common colors include green, blue-green.

Where is iowaite found?+

Notable localities include Iowa, USA; Tasmania, Australia; Quebec, Canada.

How much is iowaite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like iowaite?+

Iowaite is most often confused with Hydrotalcite, Pyroaurite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with iowaite?+

Iowaite commonly co-occurs with Serpentine, Magnetite, Dolomite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does iowaite form in?+

Iowaite typically forms in serpentinized ultramafic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is iowaite used for?+

Iowaite is used in collector, scientific research.

Find iowaite on the map

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