Description
Sometimes called "Popcorn Rocks", these gray Dolomite samples grow dazzling, white Aragonite crystals when placed in a small amount of white vinegar. This experiment is a must for any classroom studying rocks, minerals, crystals, or geology. Each set comes with complete instructions. You simply supply some small plastic bowls and the white vinegar (available at any supermarket). The crystal growing takes approximately one week depending on the temperature and humidity levels in your classroom. You and your students will be amazed!
Samples average 2 to 2.5 inches long. Sizes will vary, as this is a natural product.
Lesson Ideas
Download the pdf of this lesson!
The Origin of Popcorn Rocks...
The rocks contained in this package are magnesium rich dolomite. Dolomite is an evaporative sedimentary rock made up of a variety of sediments and minerals. This dolomite is actually somewhat unique in that it possesses an amazing property that is not necessarily common to other dolomite samples. When placed in distilled white vinegar, this dolomite grows beautiful white aragonite crystals.
This characteristic was first discovered in 1981 by Mr. Richard D. Barnes, then a geology student at the University of Utah, who was working with fossil specimens of horn coral that he had collected. Typically, horn corals are preserved in limestone, a rock that is composed of calcium carbonate, which reacts with vinegar and dissolves in that weak acid so that the fossil can be removed and studied. The interesting thing about this rock is that is did not dissolve but rather produced spectacular, white, bulbous crystals, resembling popped kernels of corn. That is how these rocks came to have the commercial name, popcorn rocks. In going back to the site, Mr. Barnes determined that this rock layer was actually an ancient lagoon that had been surrounded by a coral reef millions of years ago. He attributes the unique, crystal growing property of the rock to the residual minerals deposited in the rock layers by sea grasses that were present in the lagoon at that time.
Materials:
- Sample of Crystal growing dolomite
- Small plastic or glass bowl
- Distilled white vinegar (available from the supermarket)
Instructions:
- Place an unwashed sample of crystal growing dolomite in a small glass or plastic bowl.
- Pour distilled white vinegar over the sample until it is nearly submerged. The rock should be just barely sticking above the surface of the vinegar.
- Place the bowl with the rock on a shelf or windowsill where it can remain undisturbed but can be easily observed. The warmer the location, the faster the vinegar will evaporate and the more quickly your aragonite crystals will appear and grow.
- Observe the dolomite every day as the aragonite crystals grow atop the rock. Be careful not to touch them at this point as they are very delicate and will drop off.
- Let the bowl sit undisturbed until ALL the vinegar has evaporated and the rock is COMPLETELY DRY.
At this point, the rock may be picked up and examined. Note the beautiful aragonite crystals. Also examine the original dolomite sample and how it has changed. Proudly display your fine sample for all to see!
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Reviews
14 reviews
Amazing STEAM Project!
Jun 23, 2022
This kit worked perfectly when I taught the kids about geology and coral reefs. The customer service, shipping, packaging, and rock quality was impeccable. I couldn't recommend this class kit more!
Libby Ortiz
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St. Patrick's Day Theme
Feb 23, 2021
I've been using these rocks with my classes for years. My kids are always excited to walk in in the morning and see how much they've grown. I added green food coloring to the vinegar this time to see what would happen and the crystals did come up green. They love it!
Jody Stuart
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My Class Loves Dolomite!
Oct 27, 2020
I love sharing these with my students. It's an easy, easy science experiment and demonstrates crystal growth. The kids get so excited the next morning when they see growth on their rocks!
Jody
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Great response
Apr 24, 2020
We gave these out at the Boys & Girls Club for grab and go activities during Covid-19. The parents loved the easy project and the kids liked reporting back what happened.
Roni
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A Fun Activity
Feb 4, 2020
My Kindergarten class loved this activity. This is the third time that I have placed an order for the Dolemite rocks! It's always a hit with the children!
Patty
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Very easy and works well
Feb 22, 2019
I was surprised and impressed how easy it was to do and how well it worked.
Alan Feingold
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Worked Great
Feb 20, 2019
Used during a Science Outreach event with 3rd graders and the teachers took the Dolomite back to their classrooms. Over the next week, the vinegar evaporated and the students could watch the crystals accumulate.
Tiffany Hayden
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Fun and interesting
Apr 16, 2016
I teach preschoolers this was a spell binding thing for a student that finally got something they were struggling with the reward of getting to watch the colors in motion made both of our days
Peggy
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amazing
Feb 7, 2016
thanks for facilitating the work of parents making available the unusual materials at a good price and fast delivery
Diana
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Fun!
Jan 28, 2016
This was a fun and exciting experiment for my 4th grade students! The students were engaged and couldn't wait to see how the Dolomite would transform!
Kirsten
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lots of fun
Sep 28, 2015
my preschool class loved growing the crystals! We even used a few food coloring drops and made colored crystals
Bari
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Dolomite Crystals
Jun 3, 2015
My 8th grade students loved these. Great follow-up after studying rocks & crystals
Teresa Potts
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Growing Crystals
May 21, 2012
Rocks came sooner than I expected. Perfect size.I was so happy to find a place where I could order them. Thank you so much.
Joan Schoppe
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Crystal Growing Dolomite
May 16, 2012
Even the "small" rocks EI offers are a good size for children to enjoy watching the crystals grow. Crystals can be visible within a couple of hours - as soon as some evaporation occurs. The price is very reasonable compared to other sources of "popcorn" rocks elsewhere. The fragile aragonite can be knocked off of the dolomite and the rock can be reused several times- I guess until it all disappears.
Gwen Weatherbie
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NGSS
This product will support your students' understanding of the Next Generation Science Standards (NGSS)*, as shown in the table below.
| Elementary | Middle School | High School | ||
| 2-PS1-1 2-PS1-2 Students can use the Crystal Growing Dolomite to investigate and analyze data obtained from testing different materials to determine which materials have the properties that are best suited for an intended purpose. 2-ESS1-1Students can use the Crystal Growing Dolomite to investigate and make observations to construct an evidence-based account that Earth events can occur quickly or slowly. 4-ESS2-1Students can use the Crystal Growing Dolomite in an investigation to make observations and/or measurements to provide evidence of the effects of weathering or the rate of erosion by water, ice, wind, or vegetation. 2-PS1-45-PS1-1 Students can use the Crystal Growing Dolomite in an investigation to develop a model to describe that matter is made of particles too small to be seen. 5-PS1-3Students can use the Crystal Growing Dolomite to make observations and measurements to identify materials based on their properties. | MS-PS1-2 Students can use the Crystal Growing Dolomite to analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. MS-ESS2-1Students can use the Crystal Growing Dolomite in an investigation to develop a model to describe the cycling of Earth's materials and the flow of energy that drives this process. | HS-PS1-5 Students can use the Crystal Growing Dolomite to investigate and apply scientific principles with evidence to provide an explanation about the effects of changing the temperature or concentration of particles. HS-ESS2-1Students can use the Crystal Growing Dolomite in an investigation to develop a model to illustrate how Earth's internal and surface processes operate at different spatial and temporal scales to form continental and ocean-floor features. |
Suggested Science Idea(s)
DCI/MS-PS1.A
Each pure substance has characteristic physical and chemical properties that can be used to identify it.
2-PS1-1
2-PS1-2
2-PS1-4
5-PS1-1
5-PS1-3
MS-PS1-2
HS-PS1-5
Matter can be described and classified by its observable properties. The various kits offer students an opportunity to see crystal formation and observe how the chemical composition affects the shape and size of those crystals.
2-ESS1-1
MS-ESS2-1
HS-ESS2-1
Students can use the Crystal Growing Dolomite to observe the crystallization process in a short amount of time, modeling what can takes the Earth millions of years.
4-ESS2-1
Students can use the Crystal Growing Dolomite to build crystals and then use a variety of methods to witness erosion of the crystal formations.
* NGSS is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, this product.
