The Solution to Crystals

Greetings from Hot Springs, Arkansas. Nancy and I have had a wonderful week of digging quartz crystals. The truck is now much heavier, and we are tired but delighted. It was very hard to decide what to do for this week's experiment. I thought about another experiment with retinal fatigue, since all the digging in red clay left us seeing everything with a green hue. I also thought about revisiting the fact that you cannot identify a diamond by cutting glass. The quartz crystals we are digging scratch glass very easily. I wound up deciding on an experiment that helps explain why the crystals are here.

To see why, you will need:

  • water
  • sugar or salt
  • a pot
  • a stove
We will be heating water on the stove, so be sure that you have permission and an adult around to help.

Put about a two cups of water into the pot. Add some sugar, and stir until it dissolves. Keep adding sugar and stirring until you reach the point where no more sugar will dissolve. The solution is now saturated.

Then add about 4 more spoons of sugar. Stir and you should find that the sugar moves around, but does not dissolve. Place the pot on the stove. Turn the burner on low. As the water heats, stir it every minute or so. Very soon you should find that all the sugar has dissolved.

OK, so what does that have to do with the quartz crystals in Hot Springs, Arkansas? As you heated the water, it was able to dissolve more sugar. Making the water hotter will let it dissolve even more. Some chemicals will not dissolve at all in cold water, but will dissolve in hot water. As water gets hotter and hotter, it will dissolve more and more things.

But, the temperature of water is limited by its boiling point. When you heat water to 212 degrees F (100 degrees C), it boils, changing from a liquid to a gas. Yet, there is a way to heat water to a higher temperature, without it boiling. You have to increase the air pressure.

If you lower air pressure, water boils at a lower temperature. That is why mountain climbers have trouble cooking food. The water boils at such a low temperature that the food does not cook. Just as lowering the air pressure lowers the boiling point, raising the air pressure will raise the boiling point. With enough pressure, you would be able to heat water to very high temperatures.

At pressures of 40,000 pounds per square inch, you can raise the temperature of water up to over 6330 degrees F (3500 degrees C). At that temperature, quartz will dissolve in water. But, how can nature produce that much heat and pressure? The answer is magma, molten rock. Areas where large bodies of molten rock have melted their way near the surface tend to have hydrothermal veins. These veins are usually made up mostly of quartz, where the super heated water has been forced into cracks in the surrounding rock. As the water cools, quartz and other minerals that are dissolved in it begin to crystallize. That is how the crystals we are digging formed. Knowing the science behind them makes them even more amazing.

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