I own a few bricks that contain a weight inside of them. 52g according to Lego.
What exactly is inside of these bricks that makes them heavy?
I did the unthinkable! ...I had to know.
I opened one of my two weighted bricks. One of the two ends has a glued on cap that I've cut around using an utility knife.
The piece of metal it contains fit almost perfectly in the cavity. I don't know metals but it has a rainbowish kind of sheen to it. Here's a close up:
I'm now gluing it back with super glue.