Answer:
Glassy texture
Explanation:
The rocks that are characterized by the absence of structure, shape, and size are usually referred to as the glassy texture. These rocks are comprised of atoms that are randomly oriented. These rocks are lacking in crystals because of their faster rate of cooling. It cools so fast that it does not get a sufficient amount of time to form crystals. For example, Obsidian.
This glassy textured rocks are found in the igneous types of rocks that are formed due to the cooling of magma.