Minnesotaite is an iron-rich phyllosilicate mineral closely related to the talc group. It is found almost exclusively in iron formations, appearing as fibrous or fine-grained plates that are typically yellow-green to brownish in color.

Hardness

1-2

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineraluncommonTalc Group family

Minnesotaite

Hardness: 1-2
Luster: Pearly
Streak: White
Transparency: Translucent

Is this minnesotaite?

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 minnesotaite with a known reference. Minnesotaite sits at Mohs 1-2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Minnesotaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Minnesotaite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: yellow, green, brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy, fibrous, massive.

Often confused with

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

Often found alongside minnesotaite

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

All properties

Chemical formula: (Fe²⁺,Mg)₃Si₄O₁₀(OH)₂
Mohs hardness: 1-2
Density: 2.8-3.0 g/cm³
Colors: Yellow Green Brown
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy, Fibrous, Massive
Cleavage: Perfect Basal
Rarity: Uncommon
Uses: Collector, Scientific Research
Host rock: Sedimentary Iron Formations
Typical price: $10-50 per specimen

Where rockhounds find minnesotaite

3 mapped spots

Classic worldwide localities

Mesabi Range, Minnesota, USA
Cuyuna Range, Minnesota, USA
Gunflint Iron Formation, Ontario, Canada

Field-hunting tip

Look in sedimentary iron formations country — that is the host setting where minnesotaite typically forms. If you start seeing magnetite, hematite, stilpnomelane in float, you are in the right ground. Field specimens usually show a platy, fibrous, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Minnesota — start trip planning there.

Browse 3 U.S. spots for minnesotaite →

Common questions

How do you identify minnesotaite?+

Mohs hardness is 1-2. It typically shows a pearly luster. The streak is white. Common colors include yellow, green, brown.

Where is minnesotaite found?+

Notable localities include Mesabi Range, Minnesota, USA; Cuyuna Range, Minnesota, USA; Gunflint Iron Formation, Ontario, Canada.

Can I find minnesotaite in the United States?+

RockHoundR maps 3 minnesotaite rockhounding spots across 1 U.S. states — the top states are Minnesota.

How much is minnesotaite worth?+

Typical asking prices fall in the range of $10-50 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like minnesotaite?+

Minnesotaite is most often confused with Talc. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with minnesotaite?+

Minnesotaite commonly co-occurs with Magnetite, Hematite, Stilpnomelane, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does minnesotaite form in?+

Minnesotaite typically forms in sedimentary iron formations. Working float back to the host body is the standard way to chase a fresh occurrence.

What is minnesotaite used for?+

Minnesotaite is used in collector, scientific research.

Find minnesotaite on the map

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