How to verify a coin is gold?

[Southbay]

Howdy folks! I'm new to this forum are relatively new to coin cleaning & collecting.
I recently purchased a batch of uncleaned roman coins and have been working on them with olive oil & brushes.

One of the uncleaned coins was about the diameter of a half dollar and 3 times as thick. It was more like a rock than a crusty coin. Olive oil wasn't loosening anything on this one. I finally went at it with a steel brush & scalpel to get through the outer layers.
What I found looks like gold to my untrained eye!
This "coin" isn't very coin-like other than being generally round and about the size of a quarter though. No identifiable features at all.
How can I determine if it is really gold?
If it is gold, is there any reason to preserve this as an ancient coin rather just sell it as a gold nugget?

[Southbay]

Here is a picture of it:

[peterplanchet]

This looks coin-like -- but so corroded you can't see much. I think I see traces of a design. You might try to measure its density to see if it matches gold.

[woodenrory]

hmm i'm not an expert but you can try brushing it and if changes it's appearance it's a fake

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To fight off inflation everyone should be purchasing Gold and Silver in some form - Gold Coins - Silver Coins or bullion / bars

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