what is this fool's silver stuff in the sand?

[dochou]

I bought some Caribsea sand from Petco: https://www.petco.com/shop/en/petco...hSTXM9FRq8xUDu_JMGWfxzIC9gLM3TAhoCqcMQAvD_BwE

I'm not sure what they're calling the sand, but it's supposed to be reef safe and looks like oolite sand. It doesn't say where it came from either.
So when I rinsed the sand I noticed there were flecks of silver in it. It looks just like fools gold seen in lakes and rivers here in California. I didn't put in the tank because I've never seen anything like this in the ocean or in a reef tank. Otherwise the sand looks okay. The color is more tan than white once it gets wet.

Anyone know what the silver flecks are?
I'm guessing it's not reef safe. So I plan to stay away from it.
Thanks.

 

[StatelineReefer]

I'd need to see a picture, but judging from what I've read, it's not aragonite or crushed coral, is ph neutral, and won't increase KH, so... silicate. It's a silicate sand.

 

[dochou]

yeah, I think your right. The sand at the beach hear in SF has these silver flecks in it too. But what are the silver flecks?
I'm definitely not using this sand.

 

[StatelineReefer]

Mica flakes. Same stuff that gives automotive paint a 'metallic effect'. I would not use it on anything that did not live in an actual desert. Lizards love it... fish and sand dwelling inverts, not so much. Things around a reef expect calcium carbonate as their sand, much of their metabolism is based around it.