Proxidecagonite is a rare aluminum nickel iron mineral, typically gray to black. It occurs in shock metamorphosed portions of a CV3 carbonaceous chondrite meteorite. It was first described from material found in Russia (meteorite).

Hardness

6-7

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareQuasicrystal Group family

Proxidecagonite

Hardness: 6-7
Luster: Metallic
Streak: Black
Transparency: Opaque

No image

Is this proxidecagonite?

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 proxidecagonite with a known reference. Proxidecagonite sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: gray, black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy crystals.

Often confused with

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

How to tell apart: Streak differs, so Proxidecagonite leaves black, Icosahedrite leaves gray.

Compare →

Often found alongside proxidecagonite

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

All properties

Chemical formula: Al₃₄Ni₉Fe₂
Mohs hardness: 6-7
Density: 2.619 g/cm³
Colors: Gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Platy crystals
Rarity: Rare
Uses: Collector, Scientific research
Host rock: In shock metamorphosed portions of a CV3 carbonaceous chondrite meteorite

Where rockhounds find proxidecagonite

Classic worldwide localities

Khatyrka CV3 carbonaceous chondrite meteorite found at Listvenitovyi Stream, Koryak Upland, Chukotka, Russia

Field-hunting tip

Where it forms: In shock metamorphosed portions of a CV3 carbonaceous chondrite meteorite. If you start seeing trevorite, diopside, forsterite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify proxidecagonite?+

Mohs hardness is 6-7. Luster: metallic. The streak is black. Common colors include gray, black.

Where is proxidecagonite found?+

Notable localities include Khatyrka CV3 carbonaceous chondrite meteorite found at Listvenitovyi Stream, Koryak Upland, Chukotka, Russia.

Is proxidecagonite safe to handle?+

Proxidecagonite contains nickel. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like proxidecagonite?+

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

What minerals are found with proxidecagonite?+

Proxidecagonite commonly co-occurs with Trevorite, Diopside, Forsterite, Ahrensite, Clinoenstatite, Nepheline. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does proxidecagonite form in?+

Where it forms: In shock metamorphosed portions of a CV3 carbonaceous chondrite meteorite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is proxidecagonite used for?+

Proxidecagonite is used in collector, scientific research.

Find proxidecagonite on the map

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