Here the waters from different springs leave totally different residues below the spigots. The one on the right is called "Agua da Prata" or silver water, and the residue is bright, shiny silver.
Furnas Mineral Water Fountains: Two Waters
From James Martin, About.com
Furnas Picture: A Pair of Mineral Springs, labeled with traditional Portuguese tiles
Azores Picture ©: 2006 by James Martin, licensed to AboutAzores Travel Information
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