Final answer:
The rock described is Granite, a coarse-grained, intrusive igneous rock characterized by quartz, feldspars, and minor hornblende and biotite, and is used in various construction applications.
Step-by-step explanation:
The rock in question is described as coarse-grained, phaneritic, which means the individual grains or crystals can be seen without the aid of a microscope. The color range mentioned is light to dark gray and it is composed of many dark minerals.
This rock type is the coarse-grained equivalent of Basalt, which suggests it is an intrusive igneous rock that solidified from magma beneath the Earth's surface. Based on these clues, the rock can be identified as Granite, characterized by the composition of quartz, feldspars, and minor hornblende and biotite.
Granite's appearance includes large, crystalline grains, often light-colored with occasional dark minerals, and is commonly used in countertops and buildings.