Obsidian is volcanic glass, dark and sharp, so tradition reads it as clarity born from intense experience. Its mirror-like surface is linked to self-reflection and to seeing hard truths.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.