* Cooling: Gabbro is an intrusive igneous rock, meaning it cools slowly deep beneath the Earth's surface. This slow cooling allows for the formation of large crystals.

* Color: Gabbro typically has a dark greenish-black color due to its composition, which is rich in minerals like pyroxene and plagioclase feldspar.

* Other Characteristics: Gabbro is often coarse-grained and has a granular texture.

Important Note: While gabbro is a good fit based on your description, other igneous rocks can also have similar characteristics. For a definitive identification, a geologist would need to analyze the rock's mineralogy and texture more closely.