While on vacation in Alaska, we visited the El Dorado Gold Mine near Fairbanks. After a tour and demonstrations of mining techniques during Gold Rush days, we got to do a little panning for gold. Each person was given a pan and a bag of dirt and stones. After pouring the contents into the pan, we added water from a trough and swirled it around to stir up the silt and allow the gold, which is heavy, to sink to the bottom. Even though we had watched experts, we made little progress. The reason? Concerned about discarding something of value, we were unwilling to throw away worthless stones.