Extrusive
Igneous rocks
Forms from magma that is brought to Earths surface (lava)
Lava cools more rapidly so crystals do not have time to form or are small and difficult to see
Fine grained or lacking crystals like ObsidianForms from magma that is brought to Earths surface (lava)
Lava cools more rapidly so crystals do not have time to form or are small and difficult to see
Fine grained or lacking crystals like Obsidian