Uintaite, commonly known as Gilsonite, is a naturally occurring solid hydrocarbon resin found in vein deposits within sedimentary rocks. It is distinct for its glossy black appearance and its tendency to melt and flow when heated. It is primarily found in the Uinta Basin of Utah, where it fills vertical fractures in the surrounding strata.
Is this uintaite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch uintaite with a known reference. Uintaite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Uintaite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Uintaite typically shows a bright luster.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitTypical habit: massive.
Often confused with
Uintaite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Obsidian is the harder of the two (Mohs 5-6 vs. 2-2.5); streak differs — Uintaite leaves brown, Obsidian leaves white; luster reads bright on Uintaite and vitreous on Obsidian.
How to tell apart: Luster reads bright on Uintaite and resinous on Jet.
Often found alongside uintaite
Minerals reported to co-occur with uintaite. 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
- Streak
- Brown
- Luster
- Bright
- Transparency
- Opaque
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Industrial, Collector
- Host rock
- Sedimentary Veins
- Typical price
- $5-20 per specimen
Where rockhounds find uintaite
1 mapped spotsClassic worldwide localities
- Uinta Basin, Utah, USA
- Duchesne County, Utah, USA
Field-hunting tip
Look in sedimentary veins country — that is the host setting where uintaite typically forms. If you start seeing oil shale, sandstone 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.
Common questions
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Find uintaite on the map
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