Stone found while panning

[Argentium]

It almost looks like you found a faceted garnet that has fractured - cool find for sure !

 

[Bisquitlips]

Could it be something like a sequins that has fallen off and made its way to where you found it. That is my best guess for now and per the photos you posted. It does look "tooled" and sequins was likely glued on so there would be no sign of a eyelet for sewing to the clothing.

 

[DDancer]

No mistake those are garnets. Your probably very close to the source since garnets tend to fracture out the further they travel. Keep an eye out for those large ones

 

[ChampFerguson/TN]

Take it to a rockshop, college geology dept, rockshow, jeweler, or something like that.