I am talking about both Yield and Layout. Let me explain how the OP2 mining beacon process works.
On a Map, Mining beacons are all placed in pre-defined coordinates, after that, the Beacon will than have a setting, Dynamic, or Static. If it is static, than you basically can choose weither its Rare or Common, or weither its 1 bar, 2 bar, or 3 bar. If it is Dynamic, than I believe that it completely randomizes it, it can be Common or Rare, 1 bar, 2 bar, or 3 bar.
Although, that is what I remember, I think some recent evidence has showed that they may infact be static 100 percent, with there being 'Beacon layouts' that are randomly picked from a list, which determines all mines yields and what they are at once.