Igneous rocks are classifed by their composition (basically, the elements that make up the minerals, which make up the rock) and their texture. Texture, in this case, isnīt how it feels, but rather, itīs a way to describe the shape, size, and arrangement of the mineral grains that make up the rock.
If you can see individual grains without a hand lens or microscope, the rock is coarse-grained, or phaneritic. If you cannot, the rock is fine-grained, or aphanitic, and will look like a rock that is pretty much all one color, for example, dark gray.
