When mined from the ground, quartz crystals do not have the same shiny, semi-transparent appearance as what you can buy at a gem store. Crystals or clumps of crystals that have just been collected in the mines are often covered with clay or loam encrustations and the surface of the mineral is opaque with an oxide film. Quartz crystals need to be cleaned in three steps before they become shiny and beautiful. You have to remove the clay and the earth, put the crystals to soak to remove the stains and sand encrustations, and finally you have to smooth them until they shine.
Steps
Part 1 of 3: Cleaning the Crystals
Step 1. Use an old toothbrush to remove dirt and clay
You can do a first cleaning using water and a toothbrush; do this outdoors, as clayey soil could clog the drains.
- Scrub the minerals to remove stubborn dirt. You will have to proceed in several stages, waiting for the quartz to dry between one and the other. Once dry, the clay should crack and become easier to remove.
- If the soil adheres well to the mineral, wet the crystal with the garden hose by setting the sprayer to maximum pressure. Just like you did with the toothbrush, you will need to repeat the procedure several times a day, waiting for the clay to dry with each session.
Step 2. Soak the crystals with vinegar and ammonia to remove the carbonates of lime, calcite and barite that stain the quartz
To get rid of stains, you can use vinegar and a household cleaner.
- Soak the minerals in pure vinegar, so that they are completely submerged and let them sit for 8 to 12 hours.
- Extract the crystals from the vinegar and put them in ammonia for an equal amount of time; when finished, remove them from the liquid, rinse them with water and dry them completely with a cloth.
- If the stains do not disappear after the first soak, you may need to repeat this sequence several times.
Step 3. Use a diamond saw to remove excess material
The crystal may still be mixed with substances that you do not wish to keep; also, the mineral block may have rough edges. You can cut this material away with a diamond saw, available in hardware stores; however, remember that this is quite an expensive tool, so you can borrow it from a friend or rent it.
- Lubricate the crystal with a thin layer of mineral oil before starting.
- There is no need to move the crystal or apply pressure to the saw; just put the quartz under the blade and let the machine do its work gradually.
- Remove any portions of quartz that you don't want to keep; For example, they could be stained areas that you cannot clean and that you can get rid of with a saw.
Part 2 of 3: Remove Stains
Step 1. Use water, household detergents and bleach
The simplest and safest way to soak the crystals and remove stains is to prepare a solution of water and detergent for the laundry; you can also leave them in a bleach bath overnight. If the quartz in your possession is only lightly stained, it is best to let it sit in a combination of dish soap and water or washing machine soap.
- Use a mixture of hot water and laundry detergent to wash the crystals. You can also help yourself with a soft rag to remove dirt and debris, which shouldn't resist.
- At this point, get a container that you can cover easily, such as a sturdy Tupperware-type container. Fill it with hot water and 60ml of bleach. Put the stones in the solution, close the container and store it in a safe place for two days.
Step 2. Try oxalic acid to get rid of stubborn marks
If the crystals, in addition to being covered with normal earth and dirt, are also heavily stained and have dark areas caused by iron, it may be necessary to use oxalic acid for a thorough cleaning. This substance is also used to whiten wood and you can buy it online or in hardware stores. Buy a half-kilo packet of oxalic acid and get a four-liter container. Check that the material of which the bucket is made does not corrode in contact with the acid; metal is unable to resist this substance.
- Fill the container three quarters of its capacity with distilled water and then pour in the oxalic acid; for this operation you must wear a mask, in order to avoid inhaling the substance and try to work outdoors.
- Stir the mixture using a large stick or spoon until the acid crystals have dissolved. Add the quartz and let it soak; there is no defined duration for this bath, a few hours or several days may be enough, depending on the type and extent of the stains. Check the crystals periodically and remove the clean ones from the solution.
Step 3. Be careful when handling acid
You must be extremely cautious if you decide to use this substance; only proceed if the quartz is very stained, as it is always safer to use water and bleach. However, if you've opted for oxalic acid, stick to these safety rules:
- Wear safety glasses, gloves, and a face mask;
- Always pour acid into the water, the reverse process is very dangerous;
- Get help from a friend or family member;
- Protect your work area and go slowly to avoid splashing. Baking soda can neutralize acid droplets, so you should keep it handy.
Step 4. Rinse the crystals
Once they are soaked in the acid to get rid of the stains, you can rinse them off. If you've used oxalic acid, remember to wear gloves, a mask, and safety glasses. Wash off any traces of bleach or acid using hot water; in this way, you should get rid of the last residue of dirt.
Part 3 of 3: Grinding and Polishing the Quartz
Step 1. Get the correct materials
When the crystals are clean and spotless, you should sand them until they are smooth and shiny. To perform this work you need certain tools; go to the nearest hardware store and buy:
- 50 grit sandpaper;
- 150 grit sandpaper;
- Several sheets of 300 to 600 grit sandpaper.
Step 2. Put on safety glasses, gloves and a face mask
When you sand these stones, a lot of dust rises from their surface. It may irritate the nose, mouth and eyes; you should therefore use goggles, gloves and a mask while polishing them.
Step 3. Sand the quartz with 50 grit sandpaper
To start, you need to use the rougher one, rubbing it all over the surface gently.
Make sure you work evenly, you need to avoid areas that are more or less smooth than others
Step 4. Continue sanding with 150 grit paper and work gradually to the finer one
Once you're done with 50-grit sandpaper, switch to 150-grit sandpaper, then continue with 300 to 600 sheets.
- Remember to gently sand the entire surface of the quartz.
- Make sure to sand away any blemishes or stains.
- When finished, the crystal should be bright, clear and shiny.
Step 5. Clean and scrub the stone with a soft cloth
After you have sanded it, you can use a soft fabric to give it an even more intense shimmer. Rub it with a slightly damp cloth to get rid of the residual dust left by the sanding and then let it dry. At this point, you should have obtained a clean and shiny quartz crystal.
Warnings
- Always wear rubber gloves when using liquid or powdered oxalic acid; it is a caustic substance that can cause chemical burns if it comes into contact with the skin.
- Never heat oxalic acid indoors; the fumes are very strong and irritating without adequate ventilation.
