how do characteristics of a light colored igneous rock differ from that of a dark colored one?

Question

?

Answer 1

The dark ones are called "mafic" and contain more ferromagnesian content (magnesium and iron), while the light ones are "felsic" and are rich in silica content.

Answer 2

Light colored rocks are usually what we call "felsic" and are high in quartz and feldspar content (the clear, white, and pink minerals in granite). Dark colored rocks are usually what we call "mafic", meaning they have a high content of iron-magneisum minerals; these minerals are typically dark or black. There is little quartz in mafic rocks, and the feldspar that is found in mafic rocks has a different composition (much more calcium) than in felsic rocks.