Millions of years ago hot water was trapped inside this crystal as it cooled and contracted... this vapor bubble was formed inside the quartz. : interestingasfuck
https://www.reddit.com/r/interestingasfuck/comments/y00zaq/millions_of_years_ago_hot_water_was_trapped/r/geology - Giant Arkansas Quartz Crystal
https://www.reddit.com/r/geology/comments/adhxiv/giant_arkansas_quartz_crystal/