A paleoresource is one that has little or no demand for the material extracted from it; an obsolescent material, humans no longer need it. The classic paleoresource is an arrowhead-grade flint resource; no one makes flint arrowheads or spearheads anymore—making a sharpened piece of scrap steel and using it is much simpler. Obsolescent products include tin cans, tin foil, the schoolhouse slate blackboard, and radium in medical technology.