Smaller the ratio of ceramic to legs/plated metal/plated ceramic, higher the yield per kg. Gold-plated top ceramics in DIP14-20 package are the best yielding (small ceramic like you have), then as the chip gets longer or wider, yield per mass decrease significantly. Older types mainly from soviet manufacture held more than 20-25g/kg if not soldered. Soldered less - as quite a bit of gold is lost when de-soldering. Actually, most of the gold is in the lid plating and legs plating. Braze under silicon chip inside contain les gold in general. Average of mine lots was more than 10gAu/kg for these "more modern" ones. Bigger pieces with larger and wider ceramics fluctuated between 5-13g/kg. It depends quite a bit on the manufacturer and purpose of use.
Old fingers can run higher than 5g/kg, some even 7-8g/kg. Closely cut. But as it is all the time with e-scrap, it varies. But you do not have true fingers, but instead pin-like sockets. With pins, there is no need to try to assume the yield - from very little to very good gold. But yours are pretty old, so it raises the chances of thick solid gold plate.
Nice little pile by the way.
