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Serpentine Magnetism Study, 7/8/16 by Ronald Horii
I remember going on a hike with Open Space Authority docent Paul Billig at one of the OSA preserves. He brought along a small magnet and used it to demonstrate that it would stick to serpentine rocks. I thought I'd try that, so last month, while I was hiking up Bernal Hill in Santa Teresa Park, I used some small refrigerator magnets to see if they would attract serpentine rocks. Sure enough, they did. They weren't very strong, so they could only pick up small rock flakes. I was curious to see what a strong magnet would do. On 7/8/16, I hiked up Bernal Hill again, armed with a powerful rare earth magnet. I tested it against various rocks that I found along the trail, mostly serpentine. I was able to pick up small rocks. On larger rocks, I was able to hang the magnet from them. On boulders, I looked to see if the magnet would stick to the rock. The rocks varied in their magnetic attraction. Some rocks even varied from one part of the rock to the other. Note that I'm not a geologist, so I can't tell what types of rocks these are, except for serpentine. My rockhound friends might be able to identify them.
This was a fun experiment. I might do this on interpretive hikes. It would make a good science experiment or science project subject for kids, but there are few caveats: collecting rocks is not allowed in the County Parks or most parks and preserves. Also, rare earth magnets are fragile, expensive, and can be dangerous if not handled properly. They should only be used with adult supervision, and adults should be aware of these hazards: https://www.kjmagnetics.com/safety.asp (They sell these magnets.) You can also get small ones at Michaels: http://www.michaels.com/search?q=magnets — at Santa Teresa County Park. (near Santa Teresa County Park)
I remember going on a hike with Open Space Authority docent Paul Billig at one of the OSA preserves. He brought along a small magnet and used it to demonstrate that it would stick to serpentine rocks. I thought I'd try that, so last month, while I was hiking up Bernal Hill in Santa Teresa Park, I used some small refrigerator magnets to see if they would attract serpentine rocks. Sure enough, they did. They weren't very strong, so they could only pick up small rock flakes. I was curious to see what a strong magnet would do. On 7/8/16, I hiked up Bernal Hill again, armed with a powerful rare earth magnet. I tested it against various rocks that I found along the trail, mostly serpentine. I was able to pick up small rocks. On larger rocks, I was able to hang the magnet from them. On boulders, I looked to see if the magnet would stick to the rock. The rocks varied in their magnetic attraction. Some rocks even varied from one part of the rock to the other. Note that I'm not a geologist, so I can't tell what types of rocks these are, except for serpentine. My rockhound friends might be able to identify them.
This was a fun experiment. I might do this on interpretive hikes. It would make a good science experiment or science project subject for kids, but there are few caveats: collecting rocks is not allowed in the County Parks or most parks and preserves. Also, rare earth magnets are fragile, expensive, and can be dangerous if not handled properly. They should only be used with adult supervision, and adults should be aware of these hazards: https://www.kjmagnetics.com/safety.asp (They sell these magnets.) You can also get small ones at Michaels: http://www.michaels.com/search?q=magnets — at Santa Teresa County Park. (near Santa Teresa County Park)
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