Hal:
I'm not a geologist, but I agree with Paul in China .

The absence of gold in the samples from Tortilla Creek is surprising, but then again not all prospectors can find gold in a given location.
I see the author of the report did obtain and analyze samples from the Gonzalas Needle/Government Well area, where several mines exist.
I see no relationship between this report and the Horse Stone however. While I agree the history and favorable conditions found at Tortilla Flat would have made it a good place to set up a "Campo Mayor" for a spread out mining effort, that doesn't mean the Horse is part of a cipher leading to this area.IMO.
BTW: Campo also means field or pasture......ie: pasto=campo
I have no disagreement with the definition of "cipher/cypher" as given.
Five dots only.....not six.
Two high resolution crops, first from a B/W photo
second from one of Mike M. 's photo shot of the stone at the SMHS Museum.
View attachment 809643 View attachment 809646
Perhaps, if you see another dot, you could illustrate the location on one of these crops.
Regards:SH.