Jet is a mineraloid formed from decayed wood under extreme pressure in sedimentary rocks. It is light in weight and warm to the touch, often displaying a high, glossy luster when polished, which made it a popular mourning jewelry material in the Victorian era.

Hardness

2.5-4

Mohs

Luster

Resinous

Streak

Brown

Transparency

Opaque

fossilcommon

Jet

Also: Black Amber, Gagat

Hardness: 2.5-4
Luster: Resinous
Streak: Brown
Transparency: Opaque

Is this jet?

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

Often confused with

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

igneous

Obsidian

Mohs 5-6

How to tell apart: Obsidian is the harder of the two (Mohs 5-6 vs. 2.5-4); streak differs — Jet leaves brown, Obsidian leaves white; luster reads resinous on Jet and vitreous on Obsidian.

How to tell apart: Black Tourmaline is the harder of the two (Mohs 7-7.5 vs. 2.5-4); streak differs — Jet leaves brown, Black Tourmaline leaves white; luster reads resinous on Jet and vitreous on Black Tourmaline.

Compare →

Often found alongside jet

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

All properties

Mohs hardness: 2.5-4
Density: 1.30-1.35 g/cm³
Colors: Black Dark Brown
Streak: Brown
Luster: Resinous
Transparency: Opaque
Crystal habit: Massive
Cleavage: None
Rarity: Common
Uses: Lapidary, Jewelry, Collector
Host rock: Sedimentary Shale
Typical price: $5-50 for small specimens, higher for carved artifacts

Where rockhounds find jet

1 mapped spots

Classic worldwide localities

Whitby, England
Asturias, Spain
Dorset, England
Utah, USA

Field-hunting tip

Look in sedimentary shale country — that is the host setting where jet typically forms. If you start seeing pyrite, calcite, 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 1 U.S. spots for jet →

Common questions

How do you identify jet?+

Mohs hardness is 2.5-4. It typically shows a resinous luster. The streak is brown. Common colors include black, dark brown.

Where is jet found?+

Notable localities include Whitby, England; Asturias, Spain; Dorset, England; Utah, USA.

Can I find jet in the United States?+

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

How much is jet worth?+

Typical asking prices fall in the range of $5-50 for small specimens, higher for carved artifacts. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like jet?+

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

What minerals are found with jet?+

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

What kind of rock does jet form in?+

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

What is jet used for?+

Jet is used in lapidary, jewelry, collector.

Find jet on the map

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