A lone prow of volcanic rock right off the side of Socrates Mine Road. Please let me know if there is already a name for this rock. I don't know how much climbing has gone on here in the past, but there is some serious potential for sport routes, especially on the back side of the formation. The rock is still dirty (depending on the exposure), and there is still a lot of loose rock, especially atop the formation.
From Middletown, head up CA-175 toward Cobb Mountain for 3.8 miles, then turn left onto Socrates Mine road. The Philosopher's Stone is 2.4 miles up on the right hand side of the road, no climber would ever miss it. Park, and start climbing!