Thursday, September 26, 2013

More about crystals

Salt crystals from the Great Salt Lake---small and large. Not sure what causes the difference in size. It reminds me of the difference between intrusive and extrusive igneous rock, but there's not such thing as "intrusive halite" is there? :)

In addition to watching crystallization occur in hot ice, we saw examples of it in several other solutions. We talked about the different crystal habits of various substances, and we examined salt and sugar crystals under our microscope.

It's not the first time we've talked about crystals:
We grew alum crystals in eggshells during our Easter Unit
We grew "stalactites" during our Cave Unit

But this was the first time we have made a more in-depth study of them. They are fascinating! We did two very fast demonstrations with salt crystals and epsom salt crystals. You can find instructions for crystal-growing (including how to make larger crystals using a seed crystal, which we wanted to try but didn't get to) all over the internet. We got our instructions from this page, and from the Happy Scientist.
Cardboard soaked in supersaturated salt solution. We put one outside in the (cool) wind and one inside in the oven.

As you'd expect, the crystals which formed undisturbed grew bigger and more quickly

We loved these branching snowflake-shapes that formed on the edges

These are Epsom Salt Crystals

These are crystals that form when you freeze orange juice

We took a field trip out to the Great Salt Lake (we were actually hunting for oolitic sand, which I'll show in another post) and stopped to observe Salt Crystals along the edges of the lake. We've been to the Salt Flats, and they're amazing, but you can get some of the effect closer to home (our home, that is) near the Morton Salt Plant. There are several areas you can stop by the road and walk out onto the salt. Sometimes it's a bit mushy, but dry enough at the edges, and the crystal formation is amazing!

A few more resources for learning about crystals:

This video tells about cutting diamonds (and making them into jewelry)

Pink diamonds!

More about diamond cutting (it's in the first segment of this video).

I found this explanation of nucleation helpful.

No comments:

Post a Comment

Related Posts Plugin for WordPress, Blogger...