We are often asked about how to clean different minerals. The simple rule to cleaning minerals is that there is no simple rule!
Because minerals are made of different compositions they need to be cleaned in different ways. For example, I recently looked at a collection that had some really neat halite (salt) crystals and formation. Unfortunately, they were cleaned with soap and water making them not so neat.
Quartz is made of silicon dioxide, the same thing as glass. So anything you can clean glass with will clean quartz.
Often when quartz is found in the ground it has a white crust. This is usually, but not always, calcium carbonate. This will clean off easily with hydrochloric acid (sold as muriatic acid in the hardware stores). Just soak it until the acid stops fizzing. If there is still white crud, start over and do this until the white crud is gone.
If there is a rust-colored staining on the quartz, it will not come off with hydrochloric acid. But it will come off with oxalic acid. Oxalic acid can be used to remove rust from many minerals that are not acid sensitive (which are mostly carbonates).
Just soaking rusty quartz in oxalic acid may not remove
heavily stained quartz. The easy solution to this is to purchase a “crock pot” from Deseret Industries. Mix your oxalic acid solution and let the quartz boil in the solution, OUTSIDE, for a day or so, checking it often. Oxalic acid is very corrosive and if left open indoors, it will make all metal rust.
Even stainless steel will rust upon contact with oxalic acid vapors. Use it outside, in a well ventilated area-away from pets and children.
This method of cleaning doesn’t work on a lot of other minerals. If you want to clean other minerals you can contact us for information.
When mixing the oxalic powder with water, make sure you use distilled water only. Any other water will have impurities that will precipitate out on the quartz as a white crud. Keep in mind that oxalic acid is poisonous. Its oxalic acid that makes rhubarb leaves poisonous. Wear acid gloves and safety goggles! It is always a good idea to have some baking soda close at hand incase of spills.