After posting information on the Black Mountain Mine, several people left comments that I had not explored the full extent of the site and that there was some mines that could be explored further up the valley. A few weeks ago, I went back and found that there was two more mine shafts that you could enter. These were not full mines, as one only goes back about 25ft, and the other about 75ft. I believe these were some exploratory digs rather than the actual mine, which is collapsed. To get there, head southwest from the concrete flume (uphill) about 200ft. You will see a smaller hole in the rock to the right. This is the smaller of the two mines.
If you go just a few more feet up the hill, there is a path that leads to the left where there is an entrance to the bigger mine. This is the one that goes about 75ft into the mountain. There are some old wooden support beams laying on the ground. I posted a video on youtube of the two mine shafts.
As always, please be careful exploring and ALWAYS tell someone where you are going. If you want any more information on this location, don’t hesitate to contact me. Patrick@abandonedsandiego.com