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Cleaning Crystals

Cleaning crystal is a three step process. The clay or soil must be washed off first. Second-, the iron oxide film is removed with oxalic acid and last the crystal is washed with fresh water. Sounds simple but there are many ways to do each step.— type of crystal and quantity you have to clean.

Points can be done with a hose, crystal clusters may require pressure washing to get out the dirt: let dry in the sun and then wash again till clean. If all the dirt is not removed it will combine with the oxalic acid and prevent the removal of the iron stain. Oxalic acid may be bought at most drug stores , cleaning supply houses or rock shops. It should not be expensive. Mix the oxalic acid one pound to 2 gallons of water. It is safest to let the crystals with the acid solution sit in the sun for several days, or if in a hurry you may heat the solution. Small amounts can be heated in an old crock pot—larger amounts may need a large pan over a hot plate. Never use aluminum!! Do all this in a well ventilated area (preferably outside) and wear protective gloves. Be sure to neutralize the acid with baking soda, lime or ashes from the fireplace before discarding it.

When the crystals are removed from the acid wash with liberal amounts of fresh water. If you are unsatisfied with the results repeat all three steps as many times as necessary to get the results you are satisfied with.

If the crystals have a sandstone base it may turn green in the acid. To prevent this heat the clusters in clean water before putting them in the acid bath. This will open the pores in the sandstone and fill them with water preventing the acid from entering the sandstone.

For small cleaning jobs you can use the product called “Iron Out” which is used to remove rust stains from porcelain. It is a bisulfate cleaner sold at Home Depot. It is fairly cheap, quick and did a good job. 3 Tbsp per cup of water cleaned a few points at a time. One bottle did a bucket full.

Muriatic acid may be used for very heavily stained crystals but is nasty and dangerous material so it is a last resort and used following all recommended safety precautions.