The identification of aphanitic-textured igneous rocks can often be frustrating. When no minerals are visible we have to rely on color, a poor means of identifying a rock. When a few mineral grains are present as phenocrysts in a fine-grained matrix, these can be very helpful in the identification. The table below lists the minerals you may find in each of the common aphanitic igneous rocks and their approximate colors. If your sample does not appear to have an aphanitic texture or any of the minerals below. Go Back to the previous step.