It looks like it has evenly spaced screw holes down the length of each side like a large stainless door kick plate would have.
If a tornado can stick a piece of straw several inches into a telephone pole, how far would a large stainless panel dropped from an airplane several thousand feet above penetrate into whatever that dessert surface is made of?
If I was going to pull off an art prank like this I might make it the same size or proportions as the 2001 space odyssey monolith. Then cover it in some bullet proof metal like Tungsten sheet then fill with concrete on site then weld the top on and machine it perfect. I would want anyone trying to cut or drill into it to ask WTF is this stuff? Then maybe toss some really powerful Neodymium magnets in the concrete mix to stir up more controversy.
How bout some heating elements inside connected to a bank of buried batteries and a proximity sensor? You would only have to heat it once or twice to get enough people freaked out to start praying to it. I would want it to appear as a completely solid rare earth or not from this earth material and every time they throw another test at it to prove what its not, it raises more questions until you have a small city of people camped out near it thinking its "a sign" or an encounter.
Anyone want to help fund something like this? If it takes off we would need RR to erase this post......