Metal shielded building wire

I just went back to the dumpster where i found my lights and to my surprise i found a ton of this wire.

Most had no copper in it, it was just the metal shielding.

I tried a magnet on it and it wont stick. Is this metal stanless or alum? It's really light.

Also picked up a bunch of brass office door handles and a bunch of fire alarm strobes. Gona try and sell them on craigslist.

Usually aluminum. Malled Mc metal clad or bx. put in aluminum pile.

Take a torch to some of the sheilding. If its AL it should melt since it is so thin. SS wont melt but will glow cherry red from the heat.