Ahrensite is a rare high-pressure mineral of the spinel group, discovered primarily in shocked Martian meteorites. It forms as a result of the transformation of olivine under the extreme temperatures and pressures experienced during cosmic impact events.

Hardness

Mohs

Transparency

Translucent

mineralrareSpinel Group family

Ahrensite

Hardness: 8
Transparency: Translucent

No image

Is this ahrensite?

3-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 ahrensite with a known reference. Ahrensite sits at Mohs 8, softer than the next harder reference, harder than the previous one.
2
Match the color range
Compare against the expected color range: bluish green.
3
Look at form & habit
Crystal system: cubic. Typical habit: octahedral crystals.

Often confused with

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

How to tell apart: Ahrensite is noticeably harder (Mohs 8 vs. 5.5-6.5).

How to tell apart: Ahrensite is noticeably harder (Mohs 8 vs. 5.5).

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Often found alongside ahrensite

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

All properties

Chemical formula: Fe₂SiO₄
Mohs hardness: 8
Density: 4.26 g/cm³
Colors: Bluish green
Transparency: Translucent
Crystal system: Cubic
Crystal habit: Octahedral crystals
Rarity: Rare
Uses: Collector
Host rock: From the transformation of fayalite-rich rims of olivine megacrysts or Fe-rich microphenocrysts in contact with shock melt pockets in an olivine-phyric shergottite meteorite [TL]

Where rockhounds find ahrensite

Classic worldwide localities

Tissint meteorite
Zagami meteorite

Field-hunting tip

Where it forms: From the transformation of fayalite-rich rims of olivine megacrysts or Fe-rich microphenocrysts in contact with shock melt pockets in an olivine-phyric shergottite meteorite [TL]. If you start seeing bridgmanite, ringwoodite, wüstite in float, you are in the right ground. Typical habit: octahedral crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ahrensite?+

Mohs hardness is 8. Common colors include bluish green.

Where is ahrensite found?+

Notable localities include Tissint meteorite; Zagami meteorite.

What rocks look like ahrensite?+

Ahrensite is most often confused with Spinel, Magnetite, Chromite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ahrensite?+

Ahrensite commonly co-occurs with Bridgmanite, Ringwoodite, Wüstite, Stishovite, Olivine, Ilmenite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ahrensite form in?+

Where it forms: From the transformation of fayalite-rich rims of olivine megacrysts or Fe-rich microphenocrysts in contact with shock melt pockets in an olivine-phyric shergottite meteorite [TL]. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ahrensite used for?+

Ahrensite is used in collector.

Find ahrensite on the map

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