PART B : CLEANING CRYSTALS
This article is going to focus on quartz. Newly dug quartz crystals are often stained reddish-brown from iron and crusted with clay, when they're not coated with tougher substances such as limonite or calcium deposits. Getting these off to display the sparkling beauty beneath can be a lot of work, but the right techniques and cleaners will help.
1st Step in Cleaning your Quartz
A) The first step is to get rid of the clay. For a few prize specimens, tools such as an old toothbrush will do the job. If you have many to clean, however -- particularly if they are intricate formations -- leave them to dry in the shade until the clay cracks. Then hose them off hard with your spray nozzle set for as much pressure as your system will provide. Often you will need to repeat this step several times, allowing the clay to completely dry again between hosings.
Don't do this in your sink because clay can clog your pipes!
TIP ALERT : If your sample has organic material on it, like algae, use household bleach to clean it. Be sure to let it dry for a day before using any acid cleaning method.
B) Now that your crystals have been soaked and you have been able to remove as much clay as possible, it's time to prepare the station and material to get your crystal specimen sparkling! Please make sure you are in a well-ventilated area or outdoors due to the fumes caused from the acid based cleaners.
LIST of ITEMS
- Keep a large container of clear water handy to wash off any chemical spills.
- ALWAYS wear safety goggles & rubber gloves. The safety goggles are not always necessary but its a nice option especially if your eyes are sensitive to fumes. We perform the cleaning duties outside so sometimes goggles are not necessary.
- Don't work alone. Ask a friend or family member to be near by to help wipe up spills etc
- Avoid splattering.
- Never pour water into acid -- always add acid to water.
- Keep an ample supply of baking soda handy for acid spills.
- Keep an ample supply of vinegar for alkali spills.
- Oxalic acid powder -- sometimes called wood bleach -- is available at rock shops, drug stores (though this may be an expensive way to go), and cleaning supply stores.
Cleaning your Quartz Crystals
A common disfiguration of quartz crystals is a rusty staining caused by iron. Soaking the crystals in oxalic acid is the usual way to remedy this.
A) Start by putting your specimens in a plastic bucket after cleaning all the clay off them (clay keeps the acid from doing its job).
B) Cover them with distilled water and add the oxalic acid powder. Always remember to add acid to water, not water to acid!Follow the directions on the package if available. If not, you may have to try several different concentrations of solution for different soaking periods, depending on how stained your specimens are. You can start by adding 1/2 to 1 cup of oxalic acid crystals to 1/2 gallon of water in the bucket. For larger quantities, use about 16 ounces of oxalic acid to 2 gallons or more of water. Too much oxalic acid can turn quartz yellow, so if you have light staining, only use about 2 tablespoons of oxalic acid per 1/2 gallon of water. Always remember to add acid to water, not water to acid!
or, if you're in a hurry (or the staining is very heavy), you can heat the solution by standing the bucket in the hot sun. Some people use an old crock pot instead of a plastic bucket, and heat their acid solution that way. Don't heat this solution on your kitchen stove, and don't use any kind of metal container. Do this procedure outside, particularly if you heat (never boil) the acid, as it puts off poisonous fumes. Oxalic acid is mild as acids go, but rubber gloves are a good idea when handling either the acid solution or your specimens until they are well rinsed.
C) Let your mineral specimens soak for one to several days, If you are in a hurry (or the staining is very heavy), you can heat the solution by standing the bucket in the hot sun. Some people use an old crock pot instead of a plastic bucket, and heat their acid solution that way. Don't heat this solution on your kitchen stove, and don't use any kind of metal container. Do this procedure outside, particularly if you heat (never boil) the acid, as it puts off poisonous fumes. Oxalic acid is mild as acids go, but rubber gloves are a good idea when handling either the acid solution or your specimens until they are well rinsed.
The oxalic acid solution can be reused many times by just adding a little water and powdered acid each time. When it turns a deep green, you need a new batch. Neutralize the worn out solution by adding baking soda or agricultural lime (not unslaked lime from a building supply store!) until the mixture stops fizzing. Then you can pour it down the drain or out on the ground.
D) Place your mineral specimens into a separate bucket of distilled water. to rinse the acid off. Leave your specimen soaking in water for 1 hour. If the crystals start to develop a powdery coating as they dry, soak them in a baking soda solution -- about 1/3 cup to a gallon of water -- and then rinse them well. If they get a yellowish stain or coating during the process, soak the specimens in water for up to a week. For your next batch, try using a weaker solution of acid and stir the solution frequently.
Other Cleaning Challenges
If your quartz crystals are encrusted with calcite, barite, or lime carbonates, you can try cleaning them with ordinary household vinegar and washing ammonia. You'll want to soak them for 8-12 hours in full-strength vinegar. Wash the crystals well, and then soak them for the same amount of time in washing ammonia. Rinse them well and wipe dry. If this helps remove the coating, but doesn't finish the job, you can try repeating the process a couple of times.
NH Mines and Crystals