Proxidecagonite is an extremely rare natural quasicrystal found within meteorites. It exhibits a unique decagonal symmetry that does not repeat periodically, making it a subject of intense scientific interest for mineralogists and physicists.

Hardness

6-7

Mohs

Luster

Metallic

Streak

Metallic Grey

Transparency

Opaque

mineralrareQuasicrystal Group family

Proxidecagonite

Hardness: 6-7
Luster: Metallic
Streak: Metallic Grey
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. Proxidecagonite leaves a metallic grey streak.
3
Read the luster
Hold the specimen under a strong light. Proxidecagonite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: silver, gray.
5
Look at form & habit
Crystal system: decagonal. 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 metallic grey, Icosahedrite leaves black.

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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: Al₄Pd
Mohs hardness: 6-7
Density: 6.8 g/cm³
Colors: Silver Gray
Streak: Metallic Grey
Luster: Metallic
Transparency: Opaque
Crystal system: Decagonal
Crystal habit: Platy Crystals
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: CV3 Carbonaceous Chondrite Meteorites
Typical price: very high

Where rockhounds find proxidecagonite

Classic worldwide localities

Khatyrka meteorite
Chukotka, Russia

Field-hunting tip

Look in cv3 carbonaceous chondrite meteorites country, the host setting where proxidecagonite typically forms. If you start seeing icosahedrite, hollisterite, stishovite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify proxidecagonite?+

Mohs hardness is 6-7. It typically shows a metallic luster. The streak is metallic grey. Common colors include silver, gray.

Where is proxidecagonite found?+

Notable localities include Khatyrka meteorite; Chukotka, Russia.

How much is proxidecagonite worth?+

Typical asking prices fall in the range of very high. Quality, size, and provenance can move individual specimens well outside that range.

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 Icosahedrite, Hollisterite, Stishovite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does proxidecagonite form in?+

Proxidecagonite typically forms in cv3 carbonaceous chondrite meteorites. 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.