Ilesite is a rare manganese-bearing sulfate mineral typically found as secondary crusts or coatings in oxidizing sulfide deposits. It is highly unstable in humid conditions and can easily dehydrate into other sulfate species, so it should be stored in a cool, dry, and airtight container.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareRozenite Group family

Ilesite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this ilesite?

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 ilesite with a known reference. Ilesite sits at Mohs 2-3, 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.
4
Match the color range
Compare against the expected color range: green, greenish white, white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: aggregates, encrustations.

Often confused with

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

Often found alongside ilesite

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

All properties

Chemical formula: MnSO₄·4H₂O
Mohs hardness: 2-3
Density: 2.26 g/cm³
Colors: Green Greenish white White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Aggregates, encrustations
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral in the oxidized zones of sulfide deposits

Where rockhounds find ilesite

Classic worldwide localities

McDonnell claim, Montezuma district, Hall Valley, Park Co., and at the Penn mine, Summit Co., Colorado, USA
Silver King mine, Galena Hill, Yukon Territory, Canada
Chvaletice, Czech Republic
Jokoku mine, southwest Hokkaido, Japan

Field-hunting tip

Where it forms: A rare secondary mineral in the oxidized zones of sulfide deposits. If you start seeing pyrite, sphalerite, galena in float, you are in the right ground. Typical habit: aggregates, encrustations. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ilesite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is white. Common colors include green, greenish white, white.

Where is ilesite found?+

Notable localities include McDonnell claim, Montezuma district, Hall Valley, Park Co., and at the Penn mine, Summit Co., Colorado, USA; Silver King mine, Galena Hill, Yukon Territory, Canada; Chvaletice, Czech Republic; Jokoku mine, southwest Hokkaido, Japan.

What rocks look like ilesite?+

Ilesite is most often confused with Rozenite, Melanterite, Szomolnokite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ilesite?+

Ilesite commonly co-occurs with Pyrite, Sphalerite, Galena, Rozenite, Epsomite, Copiapite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ilesite form in?+

Where it forms: A rare secondary mineral in the oxidized zones of sulfide deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ilesite used for?+

Ilesite is used in collector.

Find ilesite on the map

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