Cleaning Quartz Crystals

Most of your crystals and other finds will come out of the ground encased in clay, covered in iron and even harder materials like calcite, limestone, and rhyolite. Removing each of these requires a different approach.

Most crystals and finds come with more than one substance coating them and those coatings may be obscuring delicate and fragile structures.

Before any aggressive cleaning, it is advisable to start with a thorough hand cleaning and examination with water and brushes; treat your prize finds with care. Soak in water overnight, clean and rinse thoroughly, dry completely and look them over. After this step some of your finds may be clean and ready to go; most will likely require more work however.

Depending on what you find, follow the steps below to continue cleaning your pieces. While there is no specific cleaning order typically you should start by removing all biological, clay & dirt coatings before moving onto the iron and harder deposits. As you proceed keep in mind that the more time you spend cleaning and exposing your pieces to chemicals, the more you increase the chance of damaging them. Do as much effective cleaning as possible in as short amount of time as you can.

CALCITE, BARITE, & LIMESTONE

RHYOLITE & BEYOND

WORKING WITH ACIDS

TOOLS

Check yourself before you wreck yourself.

The more tools the better but here is a list of what you will need at minimum to effectively clean.

Brushes; Toothbrushes, Nail Brushes, Nylon Cleaning Brushes
Plastic Slotted Spoon or Tongs
Dental Picks
Bamboo Skewers & Toothpicks
Buckets
Safety Glasses
Rubber Safety Gloves
Mask/Respirator
High Pressure Hose

Chemicals & Acids

Distilled Water
Baking Soda
Chlorine/Bleach
Ammonia
Acetic Acid/Vinegar
Iron Out/ Super Iron Out powder
Oxalic Acid
Phosphoric Acid
Muratic Acid

Optional Items

Textile Spot Cleaning Gun
Ultrasonic Cleaner
Dremel/Rotary Tool

BIOLOGICAL COATINGS

A simple soaking overnight in bleach will loosen and remove most biological coatings like moss, lichen, and roots. Use brushes and wooden tools for persistent stains.

Rinse and soak with clean tap water for 24 hours and then dry completely before exposing to any other chemicals.

Tough to reach items like roots and other debris may be removed with the textile spot cleaning gun, discussed in the clay & dirt section.

CLAY & DIRT

For pieces that are heavily coated with clay and mud start with a simple cleaning of warm water, toothbrushes, dental picks, bamboo skewers, etc. Soak the crystals overnight, brush them down and spray them off the next day. Let them dry completely allowing the remaining clay to crack and loosen. Repeat the process until the dirt and clay are removed. Be sure not to use tools that are harder than your material as they may scratch; steel for instance will scratch stone softer than quartz.

Cleaning Clusters

Go easy and use light pressure with clusters. They may be attached with only the slightest of adhesion and any pressure will sever that. Some pieces you thought were clusters may even be multiple crystals encased in a single ball of tough clay.

Deep Set Non-Mineral Coatings

If deep set dirt and debris remain after cleaning with manual means; it is time to move up to a more aggressive technique to remove stubborn deposits. This is where our favorite tool comes out! The Textile Spot Cleaning Gun. This device will almost clean rust off of specimens it is so powerful. Use with caution to remove deep set dirt and other deposits from your pieces and let dry, respray if needed. Any deposits remaining at this point call for either chemical treatments or direct mechanical removal.

TEXTILE SPOT CLEANING GUN

This is our favorite tool! It is powerful but non-destructive … mostly. It is strong enough it will break a fragile crystal so start with a junker and leave your prize finds until the end.

This device emits a high powered jet of water capable of forcing water under the skin. Use extreme care with this device. If you are using on specimens that have been in a chemical and/or acid bath, remediate the chemical before using this tool; ‘airborne muratic acid’ sounds like a 2020 headline.

Like all tools, start easy and increase pressure to remove stubborn deposits of any kind. Small flaws that look microscopic can be cracked. Be careful on combos, clusters, and plates; tenuously attached finds can be broken with this tool.

The textile gun is traditionally used in the textile printing industries to remove stains and ink overprinting from silk screening. It works wonders for cleaning specimens of any kind as long as they can handle aggressive treatment. Additionally, there is a lot of spray back as you use this so the warning to use safety glasses can not be stressed enough.

Author’s Note: I spent the afternoon with an ophthalmologist to find I had an abrasion on my cornea from spray back using a textile gun.

TEXTILE SPOT CLEANING GUN CARE

The textile spot cleaning gun is not intended for use with water unfortunately, it is meant for use with dry cleaning solution. It will work for a period of time and then the mechanism eventually freezes up. The best protection against this is to fully blow out all the water after every session and oil frequently.

IRON STAINING

Removing the red iron staining can prove to be one of the more difficult challenges of cleaning quartz and specimens and is nearly impossible to remove physically so the most common approach is with the use of chemicals; anything that breaks down rust without damaging your pieces will do. We will narrow this to the most common and readily available solutions; Iron Out/Super Iron Out, a commercial toilet and drain cleaner; oxalic acid, commonly called wood bleach; and phosphoric acid, commonly sold as stone and tile cleaner or in naval jelly. These chemicals are available through retail outlets or online.

The goal is to soften large deposits first, then persistent staining and small, micro staining. Specimens may come out clean after any of the following steps and we suggest stopping there to minimize possible damage to the finds and to reduce exposure to chemicals.

Be sure to soak your finds in water prior to any chemical treatment to saturate any matrix or host rock that may absorb chemicals.

Be sure to rinse and soak your finds in tap water for 24 hours between different steps.

IRON OUT/SUPER IRON OUT

The powdered form of this commercial drain and toilet cleaner has the active ingredient sodium dithionite. Since Iron Out is not an acid, the rust is not technically removed but softened by having its valence reduced. After soaking for the time recommended below you can use brushes and wooden tools to remove build up but do this with caution. After this process some rust will be soft enough for a textile spot cleaning gun to be effective but be sure to remediate any chemicals before trying this.
NOTE: The liquid spray form of Iron Out IS a mixture of fluorosilicic acid and oxalic acid but this is not strong enough to provide the reaction you are looking for normally.

METHOD

Mix 1 gallon of solution in a 2 gallon plastic bucket, or half the volume of your crockpot if heating, with a strong or weak mix depending on your level of staining. Soak your specimens heated for up to 2 hours or 4 hours at room temperature until the rust staining is softened or removed. Do not over soak. Remove the pieces from the solution, rinse thoroughly and soak in tap water for 1 day; changing out often. Dry thoroughly. If large pockets of rust remain you may want to run the specimens through a second round of this treatment. If your pieces are down to tough surface staining, move onto the oxalic or phosphoric acid methods.

Weak Solution: 2 ounces powder to 128 ounces distilled water

Strong Solution: 8 ounces powder to 128 ounces distilled water

DISPOSAL

Since this is a commercial drain cleaner it is safe for dumping down the drain. Filter to ensure you do not dump any remaining debris or sludge down the drain as it may damage your pipes. As a general rule we do not use our residential sewer systems for any disposal other than this chemical.

PHOSPHORIC ACID

Phosphoric acid is sold as stone and tile cleaner; this is available at most hardware stores or online.

METHOD

Pour 1 gallon of the premixed solution in a 2 gallon plastic bucket or half the volume of your crockpot if heating. Soak your specimens heated for 24 hours or 72 hours at room temperature until the rust staining is removed. Do not over soak. Remove the pieces from the solution, rinse thoroughly and soak in tap water for 1 day; changing out often. Dry thoroughly. Move onto the oxalic acid method.

DISPOSAL

Phosphoric acid should not be disposed of before it is neutralized. While it is not necessary to neutralize it, we recommend it.

Slowly add baking soda or agricultural lime until the solution no longer reacts. The solution may be poured on the ground or down the drain at this point. Filter to ensure you do not dump any remaining debris or sludge down the drain as it may damage your pipes. As a general rule we do not use our residential sewer systems for any disposal. We recommend pouring this directly on the ground after it is neutralized.

Alternate disposal method. Phosphoric acid may be diluted to half strength and spread widely on the ground as a fertilizer; the salts produced work well for this purpose; however, any contaminants from residual treatments or finds may not be good for the soil.

OXALIC ACID

Commonly referred to as wood bleach; this is available at most hardware stores or online.

METHOD

Mix 1 gallon of solution in a 2 gallon plastic bucket, or half the volume of your crockpot if heating, with a strong or weak mix depending on your level of staining. Soak your specimens heated for 24 hours or 72 hours at room temperature until the rust staining is removed. Do not over soak. Remove the pieces from the solution, rinse thoroughly and soak in tap water for 1 day; changing out often. Dry thoroughly. If any rust staining persists repeat this method.

Weak Oxalic Solution: 2 ounces acid to 128 ounces distilled water

Strong Oxalic Solution: 8 ounces acid to 128 ounces distilled water

DISPOSAL

Oxalic Acid should not be disposed of before it is neutralized.

When the oxalic acid solution can no longer we recharged and has turned a dark green color it is time to dispose of it but it must be neutralized first.

AMMONIA

To neutralize and remove any and all chemicals from your specimens after these methods, run them through an ammonia bath for 24 hours. Do not over soak. Remove the pieces from the solution, rinse thoroughly and soak in tap water for 1 to 2 days; changing out often. Dry thoroughly.

CALCITE, BARITE, & LIMESTONE

Again, chemicals are the common way to clean off these coatings. Usually acetic acid (vinegar) or formic acid are used; however stronger acids like muratic acid can be used if needed. After these treatments be sure to soak with clean water as suggested to remove all residual chemicals.

CALCITE & CARBONATES

These acids will react with any carbonate and dissolve it. Your crystals may have calcite crystals or deposits that you do not want to remove. You may have pieces held together with calcite that will fall apart in these acids.

Do a test with a junker first!

ACETIC ACID

Acetic acid is the active acid in vinegar.

METHOD

Use 1 gallon of vinegar undiluted in a 2 gallon plastic bucket. Soak your specimens for 2 hours at a time until the deposit or staining is softened or removed. Do not over soak. If the staining does not come off after 2 days, move to muratic acid. Remove the pieces from the solution, rinse thoroughly with tap water and dry thoroughly.

MURATIC ACID

This commercial pool cleaner and concrete etcher is a diluted version of hydrochloric acid. This can be purchased at any home repair store or online. This method assumes using the 31.4% solution.

METHOD

Use 1 gallon of the acid straight, or diluted with distilled water, to equal 1 gallon of solution in a 2 gallon plastic bucket depending on your level of staining. Work in small controllable batches and do not overload your solution; there will be evaporation as you go so anticipate volume loss. Lower your specimens into the solution slowly with the slotted spoon or tongs. Soak your specimens for 2 hours at a time until the deposit or staining is softened or removed. Do not over soak. Remove the pieces from the solution and soak in a baking soda and water solution for 1 day and then in tap water for 3 days, changing out often. Dry thoroughly.

Weak Muratic Solution: 64 ounces acid to 64 ounces distilled water

Strong Muratic Solution: 128 ounces acid

Baking Soda Solution: 2-3 ounce baking soda to 128 ounces distilled water

DISPOSAL

Muratic Acid should not be disposed of before it is neutralized.

Slowly add baking soda or agricultural lime until the solution no longer reacts. The solution may be poured on the ground or down the drain at this point. Do not dump any remaining debris or sludge down the drain as it will cause damage. As a general rule we do not use our house sewer systems for any disposal. We recommend pouring this directly on the ground after it is neutralized.

RHYOLITE & BEYOND

Some coatings and deposits will resist even the toughest chemicals. At this point you will need to move to mechanical physical removal.

We have already introduced the textile spot cleaning gun however it should be listed here again as it falls under the mechanical removal methods. An ultrasonic cleaner wont remove rhyolite but it is a physical cleaning method to add to your cleaning arsenal.

ULTRASONIC CLEANER

This tool has been used for decades to clean jewelry and machine parts. Use with care, especially on fragile finds.

Follow manufacturer directions. Don’t overload your batches. Check specimens often.

DREMEL/ROTARY TOOL

When all else fails grab the Mohs Scale and some physics (and a diamond tip) and grind it off. You are essentially moving from cleaning to stone carving at this point.

Use a Foredom, Dremel or other rotary tool system that will utilize diamond and lapidary bits. Start with slow speeds and smaller bits in the beginning to see what effect you get. Since many of the deposits will be hard, but not the same hardness as the quartz, you may find the rotary tool undercuts extremely fast. Make a few passes with light, even pressure; check your work and then make another few passes. Continue to check after every few passes to avoid over grinding your specimen.

The surface you clean with this method will be rough if you stop at the basic diamond bit. To get a lapidary finish use finer and finer grits of lapidary quality sand paper or bits to polish the destructed area. Typically grinding to 600 grit minimum and polishing with Cerium Oxide or 14,000 grit diamond paste will suffice however the finer grits you use and the more time you take the better the final surface will be.

FINISHING

After all the dirt and deposits have been removed give your pieces a final hand cleaning with a toothbrush and cotton cloth to remove dust and oils from your hands. Final pieces are ready for display. Exercise caution displaying specimens that are UV reactive. When your pieces get dirty from display over time take a quick pass with the textile gun and dry.

Any questions let us know and remember, start with a junker!

ACIDS

Many of the cleaning methods mentioned on this site use chemicals. Be sure to review this section on the proper use of acids and chemicals and the manufacturer directions provided with the chemicals you purchase.

ADHERE TO THE FOLLOWING PRECAUTIONS WHEN USING ANY ACID

Use glasses and rubber gloves to protect your skin and eyes.
Mix the acid with distilled water; always add acid to water and not water to acid.
Work in small controllable batches.
Do not overload your solution.
There will be evaporation as you go so anticipate volume loss.
Lower your specimens into the solution slowly with a slotted spoon or tongs.
Have neutralizing agent on hand such as baking soda or agricultural lime for acid spills and vinegar for alkali spills.
Have plenty of water to clean up spills and to rinse and soak your finds after the chemical treatment.
Work only in a well ventilated area.
Work only in a well lit area.
Adhere to all manufacturers warnings for any chemical you use.

HEATING ACIDS

Heating acids will increase their effectiveness however the fumes created are dangerous. To try this method use an old crockpot with a plastic lid in an outdoor or ventilated area.
DO NOT TRY THIS WITHOUT A FULL RESPIRATOR.
DO NOT DO THIS ON THE STOVE IN YOUR KITCHEN.
DO NOT DO THIS WITH MURATIC ACID – IMHO

NOTE ON ACIDS & CHEMICALS WITH MATRIX AND HOST ROCK

To avoid absorbing chemicals and acids into porous host matrix, soak specimens in distilled water for 24 hours prior to chemical or acid exposure.

Drying between different steps is needed to get a good review of your cleaning progress but be sure to soak again prior to the next phase of chemical cleaning.

Cleaning Quartz Crystals