How to Grow Aragonite Crystals

These beautiful aragonite crystals are grown straight from a rocks, with just a little help from vinegar.

Grow aragonite crystals from rocks.

We do so many cool projects that never make it onto TinkerLab. I wish you could see the stacks and stacks of photo files that are just waiting to be shared here. I am seriously in need of an assistant (who’s over six years old)!

A little over two years ago we grew a batch of amazing aragonite crystals. Have you heard of these? They are incredible: easy to grow, not expensive, and they offer up a cool lesson in geology and chemistry.

After digging around in our science cabinet the other day, I found the old box of dolomite rocks, which are the base for these aragonite crystals. And there were still about 20 rocks in there, just waiting to grow crystals on them!

Without further ado, I’d like to introduce you to aragonite crystals…

How to grow easy aragonite crystals

Ingredients for Aragonite Crystals

You will only need two ingredients for this project:

Dolomite Rocks

Distilled White Vinegar

Simple, right? (Honestly, I love simple)

Grow White Aragonite Crystals

Where Can I find Dolomite Rocks?

I found the BEST source for these rocks at Educational Innovations. They’re priced fairly – you can buy 25 rock samples for just $8.95, which is AWESOME if you’re a classroom teacher or interested in gifting these to a bunch of friends as we have. I’m not affiliated with this company, just a happy customer. I’ve done a thorough search and there aren’t a lot of places to find these (easily).

Dolomite rock and aragonite crystal

How to make Aragonite Crystals

I poured the rocks into a bowl and invited each child to pick their favorite one. Flat, tall, fat – sooo many choices!

Once the rock was selected, we placed it in a small glass mason jar. We used 4 oz. mason jars by Bell (affiliate), and I find ALL sorts of uses for these in our art and science projects. We store homemade paint in them, turn them into artistic tea light holders, and use their larger cousins for our new solar lights.

You can put it in any glass or ceramic container. Because I’m hugely in favor of putting kids to work (i.e. empowering them), I then poured the vinegar into a small pitcher and invited the kids to p0ur the vinegar into the jar.

The trick is to pour just enough vinegar into the jar so as not to cover up the top of the rock. Do you see that dry spot in the bottom right picture?

How to grow (EASY) Dolomite Crystals

After five days, our crystals looked like this:

Aragonite Crystals after 5 days

About half of the vinegar had evaporated, some crystals formed along the edges of the jar, and a small mound of crystals were growing on top of our rock.

The crystals are fully formed after about two weeks, once all of the vinegar evaporates. To speed up evaporation, place the jar in a sunny window.

What is aragonite?

The rocks we used for this crystal-growing experience are magnesium-rich dolomite. Dolomite is an evaporative sedimentary rock that’s made up of sediments and minerals. This unique variety of dolomite, found in an ancient lagoon that was surrounded by a coral reef millions of years ago, will grow white aragonite crystals when it’s placed in distilled white vinegar.

Aragonite is carbonate mineral that usually forms in oceans and warm, wet environments such as caves and hot springs. will turn into calcite over time. You can read up on aragonite here.

How to Grow Easy Aragonite Crystals | TinkerLab

How to Grow Aragonite Crystals

Place your rock in a jar. You can wash the sediment off of it first, or place it in the jar as it is.

Pour distilled white vinegar over the rock until the top of the rock barely pokes above the surface of the vinegar.

Place the jar on a shelf where it will be undisturbed but easily observed, preferably a warm, sunny spot that will encourage evaporation.

Small crystals will begin to appear within a day or so.

Observe the dolomite daily to track the progress of your crystals.

Leave the jar undisturbed until ALL the vinegar evaporates and the rock is COMPLETELY DRY, which could take one to two weeks. If you move the jar before this point, the crystals may fall apart. If that happens, just place it back on the shelf and begin again.

Once dry, the dolomite and crystals can be picked up and examined. They will be hard, but a bit fragile.

More Uses for Vinegar

Vinegar and Baking Soda Experiment

How to Make Curds and Whey: A Science Demonstration

Make Natural Dyes for Painting Eggs

Try the Naked Egg Experiment (free activity from the TinkerLab book – affiliate)

STEAM Activities | Teabag Hot Air Balloon

For more ideas that circle around the theme: GROW, I’m joining a creative group of engineers, scientists, educators, and artists to share projects that circle around STEAM (science, technology, engineering, art, and math) ideas. This week’s theme is GROW, and you can see the other grow-related ideas here:

DIY Crystal Landscapes | Babble Dabble Do

10 Ways to Use Tinker Trays | Meri Cherry

Transforming Ninja Stars | What Do We Do All Day?

14 Activities with Balloons | All For The Boys

Biology of Yogurt | Left Brain Craft Brain


STEAM on Pinterest

You might also enjoy following my STEAM + STEM Activities board on Pinterest for more ideas like this.

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    • Rachelle says

      Thanks so much, Anne. I did a pretty extensive hunt for info on aragonite and it’s not widely discussed. Maybe this will help it become one of the popular kids in the crystal world!

  1. says

    I have never herd of aragonite crystals! These are incredible! Off to order some dolomite rocks STAT!

  2. catt says

    Hello! Thank you for such an awesome science experiment. I’d like to try this with my two kids. I was wondering if adding color would ruin the experiment or if it was not recommended. Thanks so much!