You can even use scouring powder and a steel brush for tougher stains, as quartz is a very durable material.
You may need to repeat this process several times. Be sure not to place the crystals in direct sunlight because this could cause them to heat up too quickly and become damaged or cracked. This method will only work to remove dried clay from your quartz crystals. If the quartz is covered in iron deposits, you’ll need to use an oxalic acid method.
You can also try removing many of the iron stains with a high pressure air tool.
You can rinse the crystals with a garden hose or in the sink the next day. Be sure to stopper the sink so that you don’t lose any of the crystals. Oxalic acid can be purchased from most drug stores in powder form.
Be sure to rinse the quartz crystals with water when you finish. If you want to make your own Iron Out cleaning solution, you can combine 33 grams of sodium dithionite, 28 grams or sodium bicarbonate, 59 grams of sodium citrate, and 800 milliliters of water. Simply swirl the mixture around until all of the chemicals are dissolved in the water.
Be sure to rinse the quartz crystals well after taking them out of the bleach solution. Let the crystals dry thoroughly (for at least one day) before you begin any other kind of chemical cleaning.
Make sure to wear rubber gloves and not fabric gloves. The acidic residue could remain on the fabric gloves or seep through to your skin.
You can do this outside on the ground and wash away the remnants with a hose. Or you can do it by using a funnel to pour the spent oxalic acid into a gallon jug and add the lime in there. Then simply throw away the jug and its contents in a trashcan or dumpster.
