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By far the largest use for silver is in the photographic industry where light-sensitive silver salts are used to produce the image on film and photosensitive papers. Next in importance is the electronics industry where silver’s superior electrical conductivity is used to advantage in contacts and other conductive devices.
Sterling flatware, electroplated ware, holloware and jewelry, brazing alloys and solders, batteries, coins, medallions, catalysts, dental and medical supplies, mirrors and bearings for aircraft all consume significant amounts of silver. Asarco refines silver to two different levels of purity: 99.9% and 99.95%. Each of these grades meets or exceeds the ASTM specifications shown in the table on the next page. Asarco casts refined silver into 1,000-troy-ounce bars which are eligible for delivery on all major world commodity markets and exchanges. |
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PHYSICAL CONSTANT
| Atomic number | 47 | ||||||||||
| Atomic weight | 107.88 | ||||||||||
| Boiling point | 2212 °C(4014 °F) | ||||||||||
| Melting point | 980 °C(1761 °F) | ||||||||||
| Crystal structure | Face-centered cubic | ||||||||||
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| Electrical conductivity, mho (0 °) | 6.29 / 10 ° | ||||||||||
PTYPICAL ANAKYSIS
| Element** | Composition | Grade | Weight*** | |
| 99.90% | 99.95% | 99.99% | ||
| Silver | 99.90% | 99.95% | 99.99% | minimum |
| Silver plus copper | 99.90% | – | – | minimum |
| Bismuth | 0.001% | 0.001% | 0.005% | maximum |
| Copper | 0.08% | 0.04% | 0.010% | maximum |
| Iron | 0.002% | 0.002% | 0.001% | maximum |
| Lead | 0.025% | 0.015% | 0.001% | maximum |
| Palladium | – | – | 0.001% | maximum |
| Selenium | – | – | 0.0005% | maximum |
| Tellurium | – | – | 0.0005% | maximum |
†Chemical analyses for various grades of silver as specified under ASTM-B413-89 (Reapproved in 1989).
**Oxygen is known to be present in refined silver. When calculating the purity of refined silver by difference, oxygen will be considered as silver.
***For the purpose of determining conformance with this specification, an observed value obtained from analysis shall be rounded off “to the nearest unit” in the last right-hand place of figures used in expressing the limiting value, in accordance with the rounding method of ASTM Practice E29. By agreement between purchaser and manufacturer, analysis may be required and limits established for elements other than those listed.