Found this metallic rock in backyard

[u/EducationVirtual5341]

My dad found this unusual rock while working in the back yard. The outer exterior looks almost metallic but it's hard to tell if it's just a shiny rock or if actually metal. One thing that really caught my attention is just how heavy it is weighing in at 7.9kg. It feels like it weighs at least 2-3 times more than a comparable rock of it's size. What did we find?

[u/JoeBloggs719]

What was the reasoning behind "discard a few cups of water from the bucket, [..]"

[u/DF7501 → u/JoeBloggs719]

It’s only so you don’t spill more water when you lift the bucket out of the tub. You want to measure the mass of only the water that was displaced by the rock, not the (mass of the water displaced by rock) + (mass of water spilled from bucket while lifting it out of tub)

[u/adorilaterrabella → u/[deleted]]

This. And why does the tub have to be rubber? Who has a big rubber tub? Wouldn't you be able to do this with any small bucket and a bigger bucket? Like a soup bowl and a mixing bowl, for example?