50.3 MB (1.6 MB compressed)
5138 x 3425 pixels
43.4 x 29.0 cm ⏐ 17.1 x 11.4 in (300dpi)
DIRK WIERSMA / SCIENCE PHOTO LIBRARY DIRK WIERSMA / SCIENCE PHOTO LIBRARY
Hydrated copper (II) sulphate crystals (CuSO4. 5H2O) next to an American one cent coin. This chemical compound varies in colour according to the amount of hydration. If no or little water is present (anhydrous), it is white or pale green. The pentahydrate (with five molecules of water for each molecule of copper sulphate) is the bright blue seen here.
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