Cleaning Geodes with Muriatic Acid (9 Tips For Beginner Collectors)

Muriatic acid is not the place that we would start when it comes to cleaning up something that is definitely a geode, or might be a geode. However, if you are thinking about using it, we’ll give you our tips for cleaning geodes with muriatic acid.

Cleaning Geodes: First Determine What You Have

When people are new to rockhounding or cleaning up rocks, they tend to jump to the products and options. The first step in every case is to confirm what the material actually is. While there are some really effective cleaners that do a great job cleaning up pieces like geodes, they can actually be quite damaging to the material.

If you are planning on using muriatic acid on your geode, the first step is 1000% to confirm that muriatic acid will not damage the geode material, and also that the muriatic acid will actually be effective.

Muriatic acid does a great job dissolving calcite, and it can also take off iron oxide stains. People like to use it to dissolve material to free up crystals, for example.

But if we are talking about the inside of a geode, the acid can actually dissolve material that is pretty/sparkly/shiny and adds a lot to the look of the inside of the geode. The end result could be that all of the crystals on the inside look beautiful but they fall out of the interior of the geode.

Muriatic acid has also been known to leave a yellow stain on crystals, which requires the use of other products to resolve.

If you are looking at the outside of a rock that you think might be a geode, but you don’t know if it is (or if the acid would hurt the material), consider getting a second opinion. Reach out to friends or family that have more experience, take them the piece and let them look it over.

Check out any of the various rockhounding forums or mineral lovers forums and post a picture of the piece there. Ask for the opinions of those who know more than you. This is a good example.

Take the piece to the local rockhound or gem hunters club and see what people say. You’ll learn a lot, you’ll have more confidence in your decisions, and

Next Step To Clean Geodes with Muriatic Acid: Decide What Stays and What Goes

Once you know what it is that you have, you can make decisions about what to do next. You can’t just throw a stone into an acid bath. You need to look at the stone and then decide what it is that your goals are. If you just throw the stone in acid willy-nilly, you might end up with changes that you did not intend.

Do you want to remove the brownish-red rust stains? Do you want to try and clean off a whiteish coating on the quartz? Does it seem like there is a coating of mud on the exterior or in the interior?

Make a list of what you want to change, and then you can start taking small steps to achieve the end result you are looking for.

In general, we recommend that you move through the cleaning up process with a geode (or any other really valuable piece) slowly with an eye to preserving the piece.

Start With Basic Cleaning: Soaking in Plain Water and Soap

Before you drop a geode in acid, like with cleaning agates, we recommend that you start by soaking the piece in water, and then scrubbing it with a brush to see what can be removed. You can use dish soap, laundry soap, or even something that is a little abrasive like baking soda.

Then soak, and scrub some more.

Once it is rinsed and fully dry, it is time to make decisions about whether additional stronger products should be used.

Move Up Through The Products Slowly to Clean Up Geodes

We like cleaning up our specimens cautiously. Start with the easiest troubles first. If the stone is caked with what looks like clay or some organic matter, consider gently scraping to see if the material can be removed. Consider power washing the material cautiously.

We don’t think it is a good idea to use a power washer on the inside of a geode, as it can loosen crystals or other materials that you don’t want to come out. But it can help clean up the outside.

To help with the cleaning process, maybe do we would do a vinegar soak, or even a weak bleach soak. Others like to use denture cleaner. This should help loosen up organic matter stains and leftover dirt, etc.

We keep a close eye on the material, watching for signs of significant chemical reaction (like a lot of bubbling which could indicate that more is happening there than we want).

If the material doesn’t clean up….THEN consider moving on to a stronger acid.

Tips For Cleaning Geodes With Muriatic Acid

We think most folks would recommend against putting a geode in muriatic acid. But if you are intend on doing it, here are some tips:

  • only use the acid in a well ventilated space
  • protect yourself with goggles, gloves, and protective clothing
  • store the solution in a place that is safe from your family and animals
  • make sure your material is completely dry before you drop it in the acid
  • completely clean the material of any other product to avoid an accidental chemical reaction
  • set up your acid neutralizer (usually water and baking solid solution) before you open up the acid so that you can take care of any drips or spills, and even clean off your gloves
  • try out a test piece before putting your main piece in the acid to see what happens (if anything)
  • if the piece doesn’t clean up, consider other options (such as polishing or cutting) instead of pursuing chemicals aggressively

Take your time, learn as you go, and be persistent. In the end, not all pieces can be developed into something show worthy.

Still have questions? Check out our Knowledge Page for more articles about cleaning rocks.