ORIGINAL: Mr67Stang
Take a magnet and run it through the sand you are landing in. Remember the magnets in your motor are probably more powerful. You will most likely find iron deposits on your magnet and they will be hard to blow off the magnet without a direct blast.
You must have a high iron content for that to be true.... and even then the percentage of metals is so low that particles tend not to stick to a magnet.
As Mr67stang said, try it with a magnet... usually though nothing sticks through attraction as sand is mostly silica, crushed rock, or crushed shell ( calcium).