Wurtzilite is a rare, rubbery, hydrocarbon-based organic mineraloid primarily found in the Uinta Basin of Utah. It occurs as massive, dark, elastic or brittle veins within oil-bearing shales and is valued by collectors of unusual organic minerals.

Hardness

3-4

Mohs

Luster

Resinous

Streak

Brown

Transparency

Opaque

mineralrare

Wurtzilite

Also: Elaterite

Hardness: 3-4
Luster: Resinous
Streak: Brown
Transparency: Opaque

No image

Is this wurtzilite?

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 wurtzilite with a known reference. Wurtzilite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Wurtzilite leaves a brown streak.
3
Read the luster
Hold the specimen under a strong light. Wurtzilite typically shows a resinous luster.
4
Match the color range
Compare against the expected color range: black, brown.
5
Look at form & habit
Crystal system: amorphous. Typical habit: massive.

Often confused with

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

mineral

Uintaite

Mohs 2-2.5

How to tell apart: Luster reads resinous on Wurtzilite and bright on Uintaite.

All properties

Mohs hardness: 3-4
Density: 1.05 g/cm³
Colors: Black Brown
Streak: Brown
Luster: Resinous
Transparency: Opaque
Crystal system: Amorphous
Crystal habit: Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Sedimentary Veins in Oil Shale
Typical price: $10-50 per small specimen

Where rockhounds find wurtzilite

3 mapped spots

Classic worldwide localities

Uinta Basin, Utah USA

Field-hunting tip

Look in sedimentary veins in oil shale country, the host setting where wurtzilite typically forms. If you start seeing bitumen, oil shale 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. In the U.S., the densest reported localities are in Utah. Start trip planning there.

Browse 3 U.S. spots for wurtzilite →

Common questions

How do you identify wurtzilite?+

Mohs hardness is 3-4. It typically shows a resinous luster. The streak is brown. Common colors include black, brown.

Where is wurtzilite found?+

Notable localities include Uinta Basin, Utah USA.

Can I find wurtzilite in the United States?+

RockHoundR maps 3 wurtzilite rockhounding spots across 1 U.S. states. The top states are Utah.

How much is wurtzilite worth?+

Typical asking prices fall in the range of $10-50 per small specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like wurtzilite?+

Wurtzilite is most often confused with Uintaite, Jet. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with wurtzilite?+

Wurtzilite commonly co-occurs with Bitumen, Oil shale. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does wurtzilite form in?+

Wurtzilite typically forms in sedimentary veins in oil shale. Working float back to the host body is the standard way to chase a fresh occurrence.

What is wurtzilite used for?+

Wurtzilite is used in collector.

Find wurtzilite on the map

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