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.

$Obsidian showing the bright conchoidal fracture and glassy black break that identify it$

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, so 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, so 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, 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.