Crystals are Cool: Making Rock Candy

Wish I Had Noted the Name
Creative Commons License photo credit: biggertree

There are so many different kinds of crystals all around us, but just what are they anyway?

Put simply, a crystal is a grouping of molecules or atoms that is organized in a specific way.  Every crystal has a unique shape and properties that make it recognizable.  In today’s experiment, we will be working with sugar crystals which are oblong and slanted on the ends.

There are a couple of things going on that contribute to the growth of sugar crystals in this experiment.  First, you will be creating a supersaturated solution by heating a saturated sugar solution and allowing it to cool.

Supersaturated solutions are solutions that are so full (of sugar in this case), that they are unstable.  The solution you will create will contain more sugar (the solute) than it can hold in a liquid form.  Therefore, the sugar must come out of solution – forming what is called a precipitate (also known as yummy rock candy).  The second mechanism that helps to form the sugar crystals is evaporation.  Slowly, the water evaporates from your solution.  As this happens the solution becomes even more saturated with sugar and the sugar will continue to come out of the solution and form sugar crystals.

Blue Sugar
Creative Commons License photo credit: karsten.planz

What you are left with is a delicious science treat!  Make sure to only eat a little at a time and keep the rest sealed in a baggie.  Also, don’t forget to brush your teeth; it is pure sugar after all!  Have fun in your kitchen lab and don’t forget to be safe!  Always include an adult when trying new experiments.

Grab a handy adult; you will need one to do this activity!

Materials:
Granulated sugar – 1 cup
Water – ½ cup
Saucepan
Food coloring
Two canning jars
Spoon

What to do:
1. Dump one cup of sugar and ½ cup of water into your saucepan.  Don’t stir it!
2. Find your adult and have them help you put it onto the stove over medium-high heat.  Wait for the mixture to come to a boil and let it boil for one minute without stirring.  If you want colored rock candy, you may add some food coloring while it boils.
3. Instruct your handy adult to pour this mixture into the two canning jars.
4. Find a place on your counter that you can let the two jars sit undisturbed for two weeks.
5. Observe them once a day.  Slowly, crystals begin to form.  When you see a crust form on top of the jars, use a spoon to carefully break the crust so the water can continue to evaporate.  Don’t do anything else to your jars other than this!
6. When you feel like you have enough crystals of the right size, have an adult help you remove them from the jar using a dull table knife.
7. Eat and enjoy!  Don’t forget to brush your teeth, it is sugar after all!

100 Years – 100 Objects: Zoisite

The Houston Museum of Natural Science was founded in 1909 - meaning that the curators of the Houston Museum of Natural Science have been collecting and preserving natural and cultural treasures for a hundred years now. For this yearlong series, our current curators have chosen one hundred exceptional objects from the Museum’s immense storehouse of specimens and artifacts—one for each year of our history. Check back here frequently to learn more about this diverse selection of behind-the-scenes curiosities—we will post the image and description of a new object every few days.

This description is from Joel, the Museum’s President and Curator of Gems and Minerals. He’s chosen spectacular objects from the Museum’s mineralogy collection, which includes some of the most rare and fascinating mineral specimens in the world, that we’ll be sharing here – and at 100.hmns.org- throughout the year.

Zoisite

Zoisite (var. tanzanite)
Merelani Hills near Arusha, Umba Valley, Tanzania

This magnificent, near-flawless crystal of tanzanite (the gemstone variety of the mineral zoisite) was found in Tanzania in 1991. As seen here, the specimen is an exceptional example of trichroism, whereby the same crystal exhibits three distinctly different colors, depending on the viewing angle. 
 
Marvel at the world’s most spectacular collection of natural mineral crystals in the Cullen Hall of Gems and Minerals at the Houston Museum of Natural Science.

You can see more images of this fascinating artifact – as well as the others we’ve posted so far this year – in the 100 Objects section at 100.hmns.org.

100 years – 100 Objects: Azurite

The Houston Museum of Natural Science was founded in 1909 - meaning that the curators of the Houston Museum of Natural Science have been collecting and preserving natural and cultural treasures for a hundred years now. For this yearlong series, our current curators have chosen one hundred exceptional objects from the Museum’s immense storehouse of specimens and artifacts—one for each year of our history. Check back here frequently to learn more about this diverse selection of behind-the-scenes curiosities—we will post the image and description of a new object every few days.

This description is from Joel, the Museum’s President and Curator of Gems and Minerals. He’s chosen spectacular objects from the Museum’s mineralogy collection, which includes some of the most rare and fascinating mineral specimens in the world, that we’ll be sharing here – and at 100.hmns.org- throughout the year.

azurite

Azurite
Tsumeb Mine, Tsumeb, Namibia

 The Tsumeb mine has produced the world’s finest azurite crystals, of which this large 11-cm crystal group on green smithsonite is one of the best examples. The highly lustrous, elongated crystals with perfect terminations, on a contrasting base, admirably fulfill the requirements of connoisseurship.

Marvel at the world’s most spectacular collection of natural mineral crystals in the Cullen Hall of Gems and Minerals at the Houston Museum of Natural Science.

You can see more images of this fascinating artifact – as well as the others we’ve posted so far this year – in the 100 Objects section at 100.hmns.org

100 Years – 100 Objects : Elbaite (on Quartz)

The Houston Museum of Natural Science was founded in 1909 - meaning that the curators of the Houston Museum of Natural Science have been collecting and preserving natural and cultural treasures for a hundred years now. For this yearlong series, our current curators have chosen one hundred exceptional objects from the Museum’s immense storehouse of specimens and artifacts—one for each year of our history. Check back here frequently to learn more about this diverse selection of behind-the-scenes curiosities—we will post the image and description of a new object every few days.

This description is from Joel, the Museum’s President and Curator of Gems and Minerals. He’s chosen spectacular objects from the Museum’s mineralogy collection, which includes some of the most rare and fascinating mineral specimens in the world, that we’ll be sharing here – and on hmns.org – throughout the year.

main-elbaite-on-quartzTourmaline Queen Mine, San Diego County, California.
North America has produced some extraordinarily beautiful specimens of elbaite, a member of the tourmaline group, but the most admired are the bright red-pink crystals with blue caps found in 1972 at the Tourmaline Queen mine. The 24-cm example pictured here is the finest of the 33 major specimens recovered and is therefore the finest North American tourmaline. The lustrous, lusciously colored, undamaged pair of crystals at the top grow from an undamaged quartz crystal and are accompanied by smaller tourmaline crystals. It has been nicknamed “The Rabbit Ears.”

Marvel at the world’s most spectacular collection of natural mineral crystals in the Cullen Hall of Gems and Minerals at the Houston Museum of Natural Science.

You can see larger and more detailed images of this rare specimen – as well as the others we’ve posted so far this year – in the photo gallery on hmns.org.