Aventurine is one of those man made stones that is often passed off as natural.
They even assign healing properties to it, like natural stones are supposed to have. I believe aventurine is supposed to increase wealth and courage.
I'm not going to disagree with the idea that crystals might have vibrations that can help people, or whatever the theory is, but aventurine is just glass mixed with metal. It's got no more healing powers than your windows, or your water pipes, which are also made of glass and metal.
As long as crystal healing sites acknowledge that aventurine is a man made material, I don't mind but it annoys me to see it being passed off as another kind of rock.