These could all go either way, hardness and other special properties are what I'm guessing would be the most accurate in determining the kind of material. luster, cleavage, streak, and color can all be affected by other factors. but I guess cleavage would also be accurate. so I guess hardness special properties and cleavage would be the most reliable.
I guess second option i.e. More potential employment opportunities and revenue because collecting recyclable material needs manpower to collect them, and secondary employment in transport i.e. to collect all the material at one place we need transport and so on!
