So Magnetic
Okay, if this happened to our phones, we’d probably be a little worried. It looks like the OP was in Tahoe where he claimed the “sand was magnetic” and got stuck to his phone. Now, wait a second. Sand is created from a process called weathering which takes hundreds to millions of years.
By the end of it, the sand has a whole bunch of elements including rocks, minerals, chemicals, and sometimes even iron shavings. So, it’s not the sand that’s magnetic but rather his phone that attracted the shavings. Either way, it would be best to keep your phone away so that it doesn’t get destroyed.