What is an Earthcache?

I like to go to Earthcaches because I usually learn something new in addition to getting credit for finding a cache and getting another smiley under my belt.  (getting credit for finding a cache is called a smiley)  This particular earthcache was cool because we found crystals.  It is located in Iowa.

According to the official geocaching website  http://www.geocaching.com/  an earthcache is described as follows:

EarthCache

An EarthCache is a special place that people can visit to learn about a unique geoscience feature or aspect of our Earth. EarthCaches include a set of educational notes and the details about where to find the location (latitude and longitude). Visitors to EarthCaches can see how our planet has been shaped by geological processes, how we manage the resources and how scientists gather evidence to learn about the Earth. For more information about EarthCaches, visit http://www.earthcache.org/.

First we had to find the crystal field....

According to the cache page at http://www.geocaching.com/:
This Earthcache is Classified as a Mineral Feature. Looks like Lou and Barb found some already....

Gypsum crystals form in several varieties:
Alabaster is a fine-grained massive material. It is an ornamental stone that has been used in fine carvings for centuries.
Satin spar is a compact fibrous aggregate that has a satin-like look that gives a play of light up and down the crystals.
Selenite is the colorless and transparent variety of gypsum crystal. The word selenite comes from the Greek for Moon and means moon rock. Selenite crystals can form as a conglomerate of several connected crystals, as crystals attached to limestone or other mineral bases, or as free-floating individual crystals that are not attached to anything.
Darryl found some too....

The selenite crystals that you find at this site are loose and located on the ground. On a sunny day, you will see the bright flashes of the sun reflecting from the surface of the crystals. They often have other minerals locked in them that produce a dark or clouded area within the crystal.
Can you see any in the photo below?

Gypsum is a major rock formed from precipitation from highly saline waters.
Saline water occurs when salt water becomes land locked and some of the water evaporates. You can see this today in the Great Salt Lake in Utah. The salts become highly concentrated as evaporation continues. At some point, the water can’t hold the salts and they start to recombine into solids. These solids are then heavier than the water and they settle, or precipitate, to the bottom producing a layer of gypsum.
Gypsum is used as sheet rock for ceilings and walls in our homes. It’s also used for many other industrial purposes. Gypsum is found in many of the sedimentation layers of rock formed during many of the ages back in time.
The chemical name for gypsum is Hydrated Calcium Sulfate. The chemistry formula is CaSO4-2(H2O). Gypsum, along with its associated crystals, has a hardness of 2 mohs. This means that it is so soft that you can scratch it with your fingernail.

Yes, I put my camera down long enough to find a few myself.

The view on the way down.....

Afterwards we stopped at the Crystal Lake Cave.  We didn't have enough time to do a cave tour, but we walked around inside the gift shop.  I want to go back another day for the tour.

So now you have a good example of what an Earthcache is.  We spent a wonderful day out with good friends, poking around a crystal field, finding crystals and even learned something new!