I left for Mammoth Lakes late Saturday afternoon and used the pull-out near the Minaret Summit to sleep for the night. With no traffic to deal with, it was only a 4-hour drive from the Sacramento area where I live. I started hiking from the Devil's Postpile Campground trailhead early Sunday morning and got on the trail to Fern Lake once over the bridge that crosses a fork of the San Joaquin River. There is a great view of Devil's Postpile soon after starting up the trail to Fern Lake. The trail also provides an impressive view of Clyde Minaret a few miles farther. At Fern Lake, the maintained trail ends and a vague use-trail continues northwest over a ridge and then drops down into the Anona Lake basin where the use-trail eventually disappears completely.
Near Anona Lake I could see a chute complete with a talus fan at its base that went all the way up to the top of the ridge to a prominent gap. This chute, which is almost due east of the south shore of Anona Lake, seemed to be the most obvious way to climb out of the Anona Lake basin. Even though this chute led to the most prominent gap on the ridge, it did not seem to be the route described by Secor, which says to ascend over benches towards a prominent gap that passes between two knobs near the top of the face. There were benches and cliffs to the south of the chute, but there was also brush and possible bushwhacking involved. The chute appeared to be the more interesting route. The last 300 feet of the chute, however, appeared quite steep and ends with a vertical wall at the top of the ridgeline gap. My only hope was very thin slot that bypassed the vertical wall on the right. The slot was only visible if I looked at the chute head-on. It appeared that one could avoid this steep portion of the chute (if the route didn't go) by going left (south) out of the chute about 350 feet below the ridgeline and contour over about a quarter mile to the next low spot on the ridge.
Ascending the first 1200 feet of the chute was class 2 and went well with only a few small, easy cliff bands to surmount. The talus was fairly solid and flat in many places, indicating that a heavy load of snow probably covers this chute most of the year. Only a few patches of snow remained at this time in late-September. I suspect crampons and ice axes would be necessary if one were to attempt this chute in the spring or even in early summer. With about 350 feet to go, the chute opened up into a small bowl. At this point, it was apparent I could continue up the chute or go left towards the other gap to the south. I decided to go up the chute and return via the gap to the south. The last 300 feet of the chute became steeper as expected, with 3 or 4 short class 3 cliff bands to overcome. Two of these sections were moderately difficult class 3. However, the route kept going with nothing more difficult than these short cliff bands and I soon reached the narrow, steep slot that bypassed the ridgeline gendarme. The slot consisted of a short class 2 scree scramble to the ridgeline. The summit of Iron Mtn. was now only a 20-minute class 2 boulder-hop from here.
There was going to be no clear views of the mountains from the summit today. Smoke from several small fires burning just to the west of Iron Mtn. took care of that. The most recent entry in the register was only two days before by Matthias Selke, a long-time SPSer, who also did a solo dayhike up the mountain via Anona Lake. But it wasn't clear if he arrived at the summit by the same route I took.
On the return, I passed the top of the class 3 chute and continued to the next low spot on the ridge, suspecting that this was the class 2 route that Secor described. It was at this point that I noticed how annoying the side-hilling had become. Iron Mtn. consists of large basalt or basaltic-like rocks which are looser and smoother than most Sierra mountains that are made of granite. About every third rock I stepped on was either loose or very smooth and slippery. All very fatiguing. I found the southern gap on the ridge, crossed over to the east side, then contoured north and down to the small bowl in the chute I had ascended. This all went class 2, but I never did pass between any knobs on top of the face, as described in Secor's guidebook. There were some knobby-like rocks on the ridge farther south, but there didn't seem to be any need to go that far south away from Iron Mtn. On a map, the two ridgeline gaps that I passed through for climbing Iron are located between the 3 highest bumps on the ridge above Anona Lake. On a 15 minute map, these 3 bumps are 10,800+ ft. (3260+ m on metric 7.5 minute maps); the class 3 chute route is between the middle and northern bumps and the class 2 route is between the middle and southern bumps.
On my way back down the trail, I observed the damage from a fire that had gone through this area some years ago. I missed this sight on the way in. A huge swath of trees had been taken out by the fire, and the damage extended up to the base of Mammoth Mtn. A finger of the fire had headed farther north and crosses the trail at the Devils Postpile boundary.
The round trip distance felt to be somewhere around 12 to 13 miles. Time was a little over 4 hours up, with a half-hour on the summit, and a little under 4 hours back down to the car. This route to Iron Mtn. was an excellent hike that should be doable in one day for anyone in reasonably good climbing and hiking shape.