Am I calling this stuff what it really is?

That bottom picture looks like it might be mostly cast pieces.

The aluminum heatsinks that you see most often in (for example) power supplies or on mobos tends to be extruded. One way to tell is that it is usually flat (it may have punched-out bits or folds), and on unfinished extrusions is the lines/striations in the material where it was pulled/stretched through the dies (or whatever they're called.) It seems that extruded alu is very light for it's size (all alu is light, of course), but is fairly stiff. Recent price at my yard is $.50 per pound.



Cast aluminum is very dull, unless it's machined, in which case it can be very shiny. The hard drive case is a good example of this. Cast alu is used where complicated shapes and machined flats need to be made. Cast alu is very strong, but brittle (like cast iron)... hit it with a hammer, and it'll shatter, leaving a jagged edge. Doesn't fold like extrusions or sheet aluminum. Recent price at my yard is $.65 per pound.

Sheet aluminum is the stuff like your pop cans, pie tins, foil, etc. Bends really easy, is very malleable. The picture third from the bottom, the pink/purple things, look like they may be sheet. Recent price at my yard went from $.45-.55 per pound, depending on if it was clean sheet/ pop cans.