Have you ever wondered what was in the dust sucked up by your vacuum cleaner?  At a glass plant, the profusion of compressed air lines, exhaust ducts, and cooling air means that there is a lot of air in circulation, all of which can contribute to a dusty environment. Filters are used to minimize the dustiness, and those filters sometimes become clogged. This EDX composition map shows the contents of one such filter. In an optical microscope, the dust looks like dirty sand, but the spectral map easily discerns between glass fragments, limestone, and soda ash. All three are batch materials used for making glass. The small amount of chlorine is due to salt.