Gilsonite is a naturally occurring solid hydrocarbon resin found in massive, brittle veins. It is known for its high luster and distinct brown streak, often appearing indistinguishable from obsidian or black glass to the untrained eye.

Hardness

2-2.5

Mohs

Luster

Bright

Streak

Brown

Transparency

Opaque

mineralcommon

Gilsonite

Also: Uintahite

Hardness: 2-2.5
Luster: Bright
Streak: Brown
Transparency: Opaque

Is this gilsonite?

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 gilsonite with a known reference. Gilsonite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Gilsonite leaves a brown streak.
3
Read the luster
Hold the specimen under a strong light. Gilsonite typically shows a bright luster.
4
Match the color range
Compare against the expected color range: black.
5
Look at form & habit
Typical habit: massive.

Often confused with

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

fossil

Jet

Mohs 2.5-4

How to tell apart: Luster reads bright on Gilsonite and resinous on Jet.

How to tell apart: Streak differs — Gilsonite leaves brown, Coal leaves black; luster reads bright on Gilsonite and dull to submetallic on Coal.

Compare →

Often found alongside gilsonite

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

All properties

Mohs hardness: 2-2.5
Density: 1.05-1.10 g/cm³
Colors: Black
Streak: Brown
Luster: Bright
Transparency: Opaque
Crystal habit: Massive
Cleavage: Conchoidal Fracture
Rarity: Common
Uses: Industrial, Collector
Host rock: Sedimentary Veins in Sandstone
Typical price: $5-30 specimen

Where rockhounds find gilsonite

1 mapped spots

Classic worldwide localities

Uintah Basin, Utah, USA
Duchesne County, Utah, USA

Field-hunting tip

Look in sedimentary veins in sandstone country — that is the host setting where gilsonite typically forms. If you start seeing calcite, quartz 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 1 U.S. spots for gilsonite →

Common questions

How do you identify gilsonite?+

Mohs hardness is 2-2.5. It typically shows a bright luster. The streak is brown. Common colors include black.

Where is gilsonite found?+

Notable localities include Uintah Basin, Utah, USA; Duchesne County, Utah, USA.

Can I find gilsonite in the United States?+

RockHoundR maps 1 gilsonite rockhounding spots across 1 U.S. states — the top states are Utah.

How much is gilsonite worth?+

Typical asking prices fall in the range of $5-30 specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like gilsonite?+

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

What minerals are found with gilsonite?+

Gilsonite commonly co-occurs with Calcite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gilsonite form in?+

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

What is gilsonite used for?+

Gilsonite is used in industrial, collector.

Find gilsonite on the map

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