Gabbro is a dark-colored, coarse-grained intrusive igneous rock composed primarily of plagioclase feldspar and pyroxene. It is the plutonic equivalent of basalt and is often found in large, deep-seated igneous bodies. Collectors frequently seek it for its structural textures and as a source for accessory minerals like magnetite or chromite.

Hardness

6-7

Mohs

Luster

Vitreous

Transparency

Opaque

igneouscommon

Gabbro

Hardness: 6-7
Luster: Vitreous
Transparency: Opaque

Is this gabbro?

4-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 gabbro with a known reference. Gabbro sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Gabbro typically shows a vitreous luster.
3
Match the color range
Compare against the expected color range: black, dark green, dark gray.
4
Look at form & habit
Typical habit: granular.

Often confused with

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

How to tell apart: Luster reads vitreous on Gabbro and vitreous to dull on Peridotite.

How to tell apart: Luster reads vitreous on Gabbro and dull on Basalt.

Compare →

Often found alongside gabbro

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

All properties

Mohs hardness: 6-7
Density: 2.7-3.3 g/cm³
Colors: Black Dark Green Dark Gray
Luster: Vitreous
Transparency: Opaque
Crystal habit: Granular
Cleavage: None
Rarity: Common
Uses: Building Stone, Decorative, Industrial
Host rock: Plutonic Environments
Typical price: $5-30 for slabs or architectural samples

Where rockhounds find gabbro

Classic worldwide localities

Bushveld Complex, South Africa
Stillwater Complex, USA
Duluth Complex, USA
Skye, Scotland
Norway

Field-hunting tip

Look in plutonic environments country, the host setting where gabbro typically forms. If you start seeing plagioclase, pyroxene, olivine in float, you are in the right ground. Field specimens usually show a granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify gabbro?+

Mohs hardness is 6-7. It typically shows a vitreous luster. Common colors include black, dark green, dark gray.

Where is gabbro found?+

Notable localities include Bushveld Complex, South Africa; Stillwater Complex, USA; Duluth Complex, USA; Skye, Scotland; Norway.

How much is gabbro worth?+

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

What rocks look like gabbro?+

Gabbro is most often confused with Diorite, Peridotite, Basalt. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with gabbro?+

Gabbro commonly co-occurs with Plagioclase, Pyroxene, Olivine, Magnetite, Ilmenite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gabbro form in?+

Gabbro typically forms in plutonic environments. Working float back to the host body is the standard way to chase a fresh occurrence.

What is gabbro used for?+

Gabbro is used in building stone, decorative, industrial.

Find gabbro on the map

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