Fake Or Real New Style Athens Tetradrachm?

What is the average diameter?
Style OK.
Not too happy about the surface texture.
Does it feel greasy to the touch?
Your assumption about burial and cleaning may be right, can't say so for sure at this stage.

Examine the edge closely, looking all around for removal of a casting sprue, or other working of the edge.

May need XRF testing for final confirmation. The ancients were not able to remove quite a large variety of trace elements; these are what you look for in an XRF test.

This is actually my coin now. Thanks for sharing your concerns. I have it listed in my ebay store with lifetime guarantee of authenticity. I know that it is a former German auction house sale. It has also been accepted as a Roma numismatic auction house consignment and the individual told me that it would sell for a similar amount as the last time. I too had issues mostly with the weight but have seen some examples in the same weight range before in reputable auction houses and even an NGC graded example in a similar weight. In terms of the surface, I had concerns although you guys pinpointed plausible explanations for the levels of surface corrosion. To summarize my impression: this is a really nice ancient and genuine example of the new style attica tetradrachm with some levels of surface corrosion. If anyone is interested in the coin, please email me.