My cat will roll on the grass, as well as on carpet and the couch, so I think it's in part a grooming thing and in part a back-scratching motion, as when horses roll. In the house, as well as outside, it's sometimes a "look at me, pat me" gesture, although she then sometimes runs away in mock (or real) alarm as I bend over to oblige. But she most frequently rolls on the gravel drive, and comes up glittering with mica specks.

I am a geologist and the phrase "Rock dust" is about as meaningless as you can get. How would you like to make biscuits from a recipe that calls for 2 c. white powder....without specifying flour or salt or baking powder or corn starch or confectioners sugar....all very different but all powders. Rock dust could just be ground up silica or ground up granite or ground up phosphate....again all different. They probably don't want to put numbers and elements down because that could be tested and they'd have to pay someone to do a series of analyses for them. Several years ago I was really bothered by someone selling ground phosphate (left over from phosphate mining). They guaranteed 1% phosphate, because that's all they were required to say. When questioned they admitted the product could be 30 or 40%phosphate, all they had to guarantee was a minimum %. Well, you could dump too much phosphate on a rose and kill much of the soil biota. And that's my rant about terms not meaning much.

Thanks! It just pleased me to see a bird that's usually very secretive suddenly come forward and enjoy itself in front of the camera. The sand and stones was an afterthought - I live in New England and it's always a pain to get a pole into the ground in between the subsurface rocks. Being on the coast, I have plenty of sand and stones. It's pouring rain now, and it must be hard for the hummers to get nectar from flowers or find insects. They're fighting over the feeder which has an umbrella over it so it's reasonably dry. Sort of like sitting on the porch with a drink watching the rain. Claire

My popcorn ceiling sheds particles from time to time. Might also be errant cobwebs. If it's near an area with steady airflow it could be just regular dust build up that's caught on the rough surface of the ceiling. I have to vacuum a pretty large circumference around my ceiling fan regularly as the ceiling is a magnet for dust caught up in the airflow.