which is harder Quartz or Diamond?
I would try a product that cleans mineral deposits. CLR should work. I do not believe that it will react with the silicon dioxide that makes up quartz. If it did then it would not be able to properly clean mineral deposits off of glass.
Oxalic acid. This can be purchased online or at most rock shops.
scrape it off, it wont hurt the Crystal
The calcite will dissolve in hydrochloric acid (found in some toilet scum cleaners). The acid will not hurt the silica.
It originated back in the late 1980's or early 1990's. Most likely it was part of the new age movement or started by someone who wanted to sell more crystals of various types. I didn't keep track but I've heard various properties attributed to different crystals i.e. one person says quartz heals and another says it increases love.
