Volcanic Rocks

noun a hard, dark, glass-like volcanic rock formed by the rapid solidification of lava without crystallization

adjective relating to or resembling obsidian

• The archaeologists found a collection of obsidian tools at the ancient site.
• I love the shiny black look of obsidian jewelry.
• That obsidian dagger is so cool!
• His heart felt as cold and sharp as a piece of obsidian.