The mineral quartz is the most abundant mineral in the earth's crust. Quartz has a glassy lustre, and is hard in comparison to many other minerals. However, the mineral can be brittle and will fracture. Samples of quartz are often dirty from the surrounding rocks or soil. Collectors and dealers clean the specimens to bring out the natural beautiful of the crystal.
Scrub the crystal surfaces with a dry brush to remove any loose material present. If dirt particles are difficult to remove with a dry brush, place the crystal in a colander or on a mining sieve. Wash the crystals with a water hose to remove the stubborn soil material. Let the crystals dry, and then repeat the process of dry brushing and water cleansing, if necessary.
Wash the quarts crystals with liquid dish soap and water. Use a toothbrush to clean remaining film from the specimens. Rinse the crystals using a water hose, and allow them to dry.
Clean the quartz with a chemical solution to remove remaining iron stains or bits of rock attached to the crystal. Iron stains on the crystals are often from the presence of either hematite or goethite minerals. Place the crystals in a bucket with an iron stain remover. Allow the crystals to soak until the crystal is clean. If the stains are stubborn or if bits of rock remain, you can use diluted oxalic acid or hydrochloric acid following the same method. Carefully rinse the chemical solution from the crystal with water, and allow the specimen to dry.
Hydrochloric acid and oxalic acid are very dangerous to handle, and you should use this material only if you are experienced with acids. Wear safety equipment such as gloves, eye goggles, and chemical-resistant coveralls during all chemical cleaning procedures. Do not use chemical solutions around children. Properly dispose of used chemical solutions.