Rocks are naturally occurring solids which are composed of minerals & have been used by humans since ages. From Stone Age, rocks are used for various purposes. Also, the metals and minerals found in rock play an important role in our life. Get to know all the Gabbro Uses. We have provided you with all information about Gabbro rock here. Gabbro is an intrusive igneous rock which is chemically equivalent to plutonic Basalt. Gabbro is available in dark grey to black colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Gabbro is black. Get to know more about Gabbro rock and characteristics of Gabbro rock in the next sections.