Susanna was hiking in the mountains, and she discovered an interesting, shiny rock. She wondered if this sample was actually a rock or if it might be a mineral. As she observed it more closely, she noted that it was solid and naturally occurring, with a definite chemical composition. The sample did not appear to have a crystal structure. An illustration of a shiny dark piece of obsidian. Could Susanna have found a mineral? Explain why or why not.