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| | Why are copper, silver, gold, iron, brass colored? (metals) |
 | | However, if the efficiency decreases with increasing energy, as is the case for gold and copper, the reduced reflectivity at the blue end of the spectrum results in yellow and reddish colors, respectively. |
 | | Gold is so malleable that it can be beaten into gold leaf less than 100 nm thick, then revealing a bluish-green transmitted-light color. |
 | | When gold is in metallic colloidal form, however, as in the 10-nm-diameter particles in "ruby glass," the very complex "Mie scattering theory" has to be used to explain the unexpected red color illustrated in Plate VIII; the yellow glass in this figure is colored by Mie scattering from metallic colloidal silver particles. |
| webexhibits.org /causesofcolor/9.html (867 words) |
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