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, 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.