| AF - Africa | AG - Silver |
| AS - Asia | AU - Gold |
| AY - Assaying, Blowpiping | CL - Coal, Lignite |
| CN - Canada | CU - Copper |
| EU - Europe | GL - Gems, Lapidary |
| GM - Geomorphology | HB - History & Biography |
| HY - Hydrology, Hydrogeology | MC - Mineralogy & Crystallography |
| MH - Mining History | MP - Cartography, Maps |
| MX - Mexico | OC - Oceanography |
| OL - Oil & Natural Gas | PF - Pacific, Australia, New Zealand |
| PG - Planetary Geology, Meteorites | QG - Quaternary Geology, Glaciology |
| SA - South America | SE - Seismology, Earthquakes |
| SP - Speleology | TC - Tectonics |
| VL - Volcanology | STATES OF THE U.S. (Use two-letter postal abbreviations) |