Where is Gabbro found?
Gabbro
Got a photo? Identify rocks instantly with the Rockby app
Open the appGabbro occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Gabbro
Oceanic Crust
Gabbro is a major constituent of the lower oceanic crust, forming beneath mid-ocean ridges. It can be found exposed in ophiolite complexes, which are fragments of oceanic crust and upper mantle thrust onto continental margins (e.g., Oman, Cyprus, Newfoundland).
Layered Intrusions
Large, economically significant layered mafic intrusions worldwide contain vast quantities of gabbro. Examples include the Bushveld Complex (South Africa), Stillwater Complex (USA), and Skaergaard Intrusion (Greenland).
Continental Rifts and Hotspots
Gabbroic intrusions are associated with continental rifting environments and large igneous provinces (LIPs) formed by mantle plumes (e.g., Duluth Complex, USA; Siberian Traps, Russia).
Mountain Ranges
Gabbro can be found in eroded mountain ranges where deep-seated igneous intrusions have been uplifted and exposed (e.g., parts of the Appalachian Mountains, USA; Scottish Highlands, UK).
Collecting tips
- Look for Dark, Coarse-Grained Rocks. Gabbro is distinctly dark and its individual mineral grains are visible without magnification. This distinguishes it from fine-grained basalt.
- Check for Mineral Composition. Identify the presence of dark pyroxene and lighter, often iridescent, plagioclase feldspar. A hand lens can be very useful for this.
- Consider the Geological Context. Gabbro is typically found in areas associated with ancient oceanic crust (ophiolites), large intrusive complexes, or areas of significant mafic magmatism.
- Examine Weathered Surfaces. While fresh gabbro is dark, weathered surfaces can sometimes appear brownish or greenish due to alteration of mafic minerals.
Quick Check
- Color:
- Dark (black, dark green, dark gray)
- Luster:
- Vitreous to dull
- Streak:
- White to very light gray (from plagioclase), or no streak (from mafic minerals)
Explore Gabbro
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.