How to clean smoky quartz? I have this piece of tumbled smoky quartz (Silicium oxide with entrapped materials giving it its black color). I accidentally left it in my clothes and it ended up in our washing machine. The detergent left a dull residue on the stone, taking the shine away.

I tried to clean it with water and afterwards with a dry cloth to rub the residue off, but both to no avail. Could anyone advise me how to clean my quartz without damaging it further?

Alternatively, the washing process may have chemically affected my specimen? The washing detergent is probably basic and silica can react with hydroxide. The temperature was cold to warm (forgot the exact program that was used). 


Two specimens of smoky quartz. The left one is affected by the washing process.
If it is residue white vinegar should remove it.  Gentle rubbing with wet Bon Ami powder also takes off combination gunk from things like fabric softener.  Laundry detergent isn't usually strongly alkaline enough to etch silicates.