Question about the black sand at my local beach in Galveston

I always thought it was just dirty until a friend told me last month it's magnetite from old volcanoes. Now I can't stop picking up handfuls and checking it with a magnet.

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2 Comments

margaret996mo ago

That's so cool it's magnetic. Read once that the magnetite gets worn down from rivers and waves over millions of years. Makes you wonder what else is mixed in there, right?

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robert646mo ago

Wait, is magnetite the main thing that makes sand magnetic? I always thought it was mostly iron minerals like hematite mixed in. @margaret99, you're right about it being worn down, but some of that black sand can also come from old volcano rock, like basalt. It's wild to picture all that stuff just grinding together for ages. Makes you look at a beach totally different.

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