Published September 13, 2013 at 1200 × 675 in Potosí: a City in the Shadow of a Mountain I don’t know what this blue goop looking stuff is, but we were strictly told not to touch or brush it as we walked past, if we knew what was good for our health. Share this: Share on Facebook (Opens in new window) Facebook Share on X (Opens in new window) X Email a link to a friend (Opens in new window) Email Like Loading...