How can I clean calcium deposits off my mirror?
Here is a little known secret, don't tell anyone!!!!  "Bar Keepers Friend"  powered cleaner works miracles with fogged, rain stained and calcium covered glass.  It contains acyclic acid and a mirco fine abrasive. It cleans glass, head light lenses  and fiberglass like crazy and give you a very smooth polished finish. you can also use it with a buffing wheel or by hand. You can find this product at most any grocery store.