Snowflake obsidian has white spots against the black that resemble snowflakes , which is due to bubbles or crystal inclusions . some obsidian displays a strong iridescence and some have a sheen from within , similar to the sheen of moonstone 也有可能是全部單色或有條紋或有斑點,最有名的是有彩虹閃光的彩虹黑曜巖rainbow obsidian ,并且有些。