The Big Picture, a photo-essay page of Boston.com, has published two series of photographs of sulfur-mining activities at the Kawah Ijen volcano in Indonesia. The first was taken during daylight hours, the second at night. Here are a few pictures to whet your appetite, reduced in size to fit this blog.
Above them, a sulfur deposit burns blue, ignited by their torches.
There are many more daytime and nighttime photographs at the links (all considerably larger than the small reproductions here). Very interesting, and recommended viewing.