In FCT_MineralDeposit, there are two fields with data regarding the deposit's original values:
OriginalAcc
HalfOriginalAmount
It appears that these fields do not (always?) get updated based on the findings of ground surveys.
Here are the two records in my database that indicate such:
GameID,MaterialID,SystemID,SystemBodyID,Amount,Accessibility,HalfOriginalAmount,OriginalAcc
119,1,14013,1270312,103680000.0,0.1,24502500.0,0.1
119,1,13991,1267757,14905800.0,1.0,230400.0,0.6
Both records have Amount more than 2x HalfOriginalAmount.
The second record also has Accessibility higher than OriginalAcc.
I know that the body of the first record had a geo survey that found additional duranium (with no increase in acc).
I don't recall doing a ground survey of the second one, but it would have happened a long enough time ago that I may have just forgotten.