Mesosiderites are a complex class of stony-iron meteorites characterized by an approximately equal mixture of silicate minerals and metallic nickel-iron. They are easily identified by their brecciated appearance, featuring dark, angular silicate fragments embedded within a bright, metallic matrix. Collectors should look for their distinct high density compared to terrestrial rocks and the characteristic Widmanstätten patterns sometimes visible in the iron components.

Hardness

5-6

Mohs

Luster

Metallic

Streak

Grey

Transparency

Opaque

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Mesosiderite

Hardness: 5-6
Luster: Metallic
Streak: Grey
Transparency: Opaque

Is this mesosiderite?

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 mesosiderite with a known reference. Mesosiderite sits at Mohs 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. Mesosiderite leaves a grey streak.
3
Read the luster
Hold the specimen under a strong light. Mesosiderite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: silver, gray, black, brown.
5
Look at form & habit
Typical habit: massive.

Often confused with

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

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Pallasite

Mohs 5-6

How to tell apart: Streak differs — Mesosiderite leaves grey, Pallasite leaves metallic grey.

How to tell apart: Streak differs — Mesosiderite leaves grey, Iron Meteorite leaves metallic gray.

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Often found alongside mesosiderite

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

All properties

Mohs hardness: 5-6
Density: 4.2-4.8 g/cm³
Colors: Silver Gray Black Brown
Streak: Grey
Luster: Metallic
Transparency: Opaque
Crystal habit: Massive
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Stony-Iron Meteorite
Typical price: $50-500 per gram depending on provenance and size

Where rockhounds find mesosiderite

Classic worldwide localities

Vaca Muerta (Chile)
Estherville (USA)
Lowicz (Poland)
Patwar (India)

Field-hunting tip

Look in stony-iron meteorite country — that is the host setting where mesosiderite typically forms. If you start seeing olivine, pyroxene, nickel-iron in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mesosiderite?+

Mohs hardness is 5-6. It typically shows a metallic luster. The streak is grey. Common colors include silver, gray, black, brown.

Where is mesosiderite found?+

Notable localities include Vaca Muerta (Chile); Estherville (USA); Lowicz (Poland); Patwar (India).

How much is mesosiderite worth?+

Typical asking prices fall in the range of $50-500 per gram depending on provenance and size. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like mesosiderite?+

Mesosiderite is most often confused with Pallasite, Iron Meteorite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with mesosiderite?+

Mesosiderite commonly co-occurs with Olivine, Pyroxene, Nickel-Iron, Troilite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does mesosiderite form in?+

Mesosiderite typically forms in stony-iron meteorite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is mesosiderite used for?+

Mesosiderite is used in collector, scientific research.

Find mesosiderite on the map

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