As a rule, things get ugly when when drillers goof up. Fly Geyser in Nevada is the exception.

A geothermal test well on private property wasn’t capped off properly in 1964 and hot water percolated up to the surface, dissolving a lot of calcium carbonate along the way. The result is beautiful.

Those colors on the travertine walls aren’t minerals. They are extremophiles thriving in this very tough environment.

Here is more information.