Final answer:
Obsidian and pumice are both volcanic rocks that consist of glass and have a basaltic composition.
Step-by-step explanation:
Obsidian and pumice have several similarities. First, both rocks consist of glass since they are formed from volcanic activity. Second, they are pyroclastic rocks, meaning they are formed from volcanic fragments that are ejected during eruptions. Lastly, both rocks have a composition that is basaltic in nature.
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