Also, a coworker of mine brought this piece in to met

[crystalraye0379]

A coworker of mine brought this piece in to me today and said he found this in our company garage lol. Pure solid, almost perfectly round, the size of a cantaloupe. I am not sure what it could be. He threw it down as hard as he could on the cement and it only broke a tiny piece off. He then tried using a sledge hammer, to no avail, only breaking off a bit of it. Not sure where it came from or what it is?! Any ideas. I searched web for rounded rocks and cldnt come up with anything.

 

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[DDancer]

Looks like a dense piece of granitiod and would take a lot of effort to break open. Cutting a slab would be easier. As to why its rounded likely its due to normal erosion possibly in a stream or river however some glacial materials form the same way. That bit just happened to be a hard nodule in the original formation.