Yep. But you could measure the hardness of even an individual sand particle. It's not impossible nor would it even require much in the way of technology to do it. An individual grain stuck to your finger and rubbed across a knife blade would do it. Just look for the scratches. Or you could embed it in a hard matrix and rub it across a knife blade. Or you could glue a whole bunch of sand grains together with some kind of silicate binder and rub it across a knife blade. Kind of like this



Sand grains bound together with a silicate binder is usually called 'sandstone'

If the sand is in a liquid matrix, they call it a polishing paste.