Enjoy our first Earthcache, inspired by our vacation to Cape Cod in 2015! The next time you're in the area, try this fun Earthcache experiment at Newcomb Hollow Beach in Wellfleet. Free parking is available right next to the beach, but a beach pass will be required during beach season (approximately Memorial Day to Labor Day).
Cape Cod quartz is a milky white crystal commonly found on Cape Cod beaches. It's silicon dioxide (SiO2), which is the second most common mineral on Earth. Cape Cod quartz pebbles were originally quartz veins which filled rock fractures in the area. It's molecules are comprised of one silicon atom and two oxygen atoms. Quartz comes in a variety of sizes, shapes, and colors, but the milky appearance of Cape Cod quartz is due to trapped gas or liquid as the quartz was forming long ago.
To try this experiment, first get two quartz pebbles and safety goggles/glasses. Next, take them to a dark place and let your eyes adjust to the darkness. Then wearing the goggles/glasses, strike the quartz pebbles by hitting or rubbing them together. You'll see the impacted areas of the quartz glow like magic!
This glow isn't actually magic, but an optical phenomenon called triboluminescence (from the Greek root tribein, meaning rub, and the Latin word lumin, meaning light).
There are two possible explanations for triboluminescence. One is when electrons within the quartz atoms are temporarily thrown out of orbit due to mechanical stress -- such as impact, friction, or breakage -- the energy released when they bounce back into orbit produces light.
The second explanation is quartz's piezoelectricity (from the Greek word piezein, meaning squeeze or press), which is produced when stress causes electrons to create an electric current. This current may ionize gases trapped within the quartz, causing it to glow, akin to the electric current flowing between thunderclouds and the ground when lightning strikes. Quartz's piezoelectricity is also why the most common industrial use of quartz is in electronic devices, such as watches, tuners, radar, and sonar.
There is no physical cache container at this location. To officially find this Earthcache, you must send us a message within one week of logging it with the correct answers to the following questions, plus the required photo in your log or message. Logs containing answers, logs without a corresponding message sent to us within one week, and logs without a sufficient photo will be deleted with or without warning.
1) What is the term for the glow caused by striking quartz?
2) What is the term for the electric current caused by striking quartz?
3) What color is the glow caused by striking quartz?
4) On the nearby building, what does the right sign facing the parking lot say (one word)?
5) Message us or post in your log a unique photo of this location with two or more pieces of Cape Cod quartz you found on this beach. You may use multiple photos and choose to be or not to be in the photo, but the beach and at least two pieces of milky quartz must be clearly visible. Fuzzy or out-of-focus photos will not be accepted, and photos in which the quartz is too far away to clearly identify will also not be accepted. Close-ups of the quartz with the beach in the background are recommended. We will compare photos to ensure someone isn't using someone else's photo. We will also check profiles to prevent armchair logging.
Sources:
United States Geological Survey
Geology.com
California State University Northridge
University of Texas at Austin Department of Geological Sciences
Special thanks to CaseyToo, Hillary Greenberg Lemos, and Maggie Gardner for helping us with this Earthcache!
Congrats to Hipointer and Capiti for FTF!