Rock Texture

In classifying rocks, it´s important to describe the texture. Fine-grained means the grains are too small to identify without a hand lens (sometimes you need a microscope!). Coarse-grained means the grains are large enough to identify without a hand lens. Glassy texture means the rock has no grains, not even under a microscope. If a rock has glassy texture, it´s volcanic, meaning it cooled from liquid magma, at or very near the earth´s surface, and it cooled too quickly for individual mineral grains to form.