What is an obsidian rocks' reaction to vinegar?

Obsidian, being a volcanic glass composed primarily of silica, does not react with vinegar (acetic acid) in the same way that limestone or other carbonate rocks do. Since obsidian lacks calcium carbonate, there is no fizzing or bubbling reaction when vinegar is applied. Instead, the surface of the obsidian may become slightly cleaner due to the acidic nature of vinegar, but there is no significant chemical reaction.