Selenite Crystals EarthCache
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To claim a find on this Earthcache, you will need at least a 6” ruler for measuring and a camera (optional). The steep slope is not advisable for small children.
This Earthcache is Classified as a Mineral Feature. 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. 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. 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. PLEASE USE RESTRAINT AND ONLY TAKE ONE OR TWO CRYSTALS. LEAVE SOME FOR OTHERS TO ENJOY. The area where the selenite crystals are located is on a steep roadside slope with no vegetation. Do not disturb the soil surface with any shovel, rake, or other tools. During wet weather this slope is very slippery and dangerous. PLEASE STAY OFF THE WET SLOPE TO PREVENT INJURY TO YOURSELF AND TO PREVENT ADDITIONAL EROSION EFFECT. To claim a find on this Earthcache, you will need a camera and at least a 6” ruler for measuring. Send an email to me through my profile page with your answers to these questions. Measure the largest crystal that you find. 1. What is the length? 2. What is the width? Compare two of the crystals. 3. What do you see that is similar about the crystals? 4. Other than their size, what do you see that is different about the crystals? 5. (Optional) Take a photo of yourself with the crystal-containing slope in the background and post it with your log. Web sites where information was obtained and where you may find more information on gypsum: http://www.galleries.com/Minerals/Sulfates/gypsum/gypsum.htm or on selenite crystals: http://www.igsb.uiowa.edu/browse/gypsum/gypsum.htm
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