A (not typical) day in the field

In early July, a hot month normally, I took a look at a mine out in the Mojave Desert that a geologist friend recommended. It was nine miles from the nearest settlement and up a really bad mine road that has been much washed out. The mine produced iron ore during WW II, but what mineral they were after wasn't specified, so I had to look. Turns out that the ore was magnetite, though mixed with an unidentified (so far) green mineral that would make specimens confusing to students. Interesting, but not surprising. What was surprising is that just as I was pulling out of the mine property, the floor-mounted gear shift lever snapped off 4" above the floor.

Luckily I was stuck in 4th gear and it was downhill all the way to the highway. There was no cell phone service out there, but that's often the case. Headed for Baker, California, hoping for no steep uphills. Finally came in range of a cell tower so stopped on a downhill and called the mechanic. "Grab the stub of the gear shift lever with a vicegrips, pull up, and you can shift while pulling," he said. Oh! And it worked, more or less.

At Baker the giant thermometer registered 113˚ F. so added ice to the cooler and headed for an outcrop at the edge of the Baxter Mine property near Cave Mountain, where a body of hematite formed when contact with an igneous intrusion caused limestone to melt and release iron - limestone often contains iron.  Baxter Mine produces a low grade hematite that goes to California Portland Cement. Completing the cycle, milled hematite is added to cement in a small percentage. The largest percentage of cement's ingredients is limestone. So out of limestone because of metamorphism, and now back into limestone during the manufacture of cement.

Trimmed specimens until dark, since the hematite outcrop was on the shady though not cool side of a hill. The zone of hematite is just off the mine road near a mess of random tracks caused by off-roaders. Unable to shift gears efficiently, got stuck in sand when I turned up a wash that I thought was the track back to the  road. Grrr!

Jacked up the dug-in wheel, shoveled away the sand, collected a bunch of flat rocks and made pavement, being sure to place the largest and flattest one I could find right under the wheel that had lost traction. Fished around with the vicegrips, finally found reverse, carefully backed out and found the right track back to the road. Got to the mechanic's shop at 3 AM and camped out. This mechanic is old school, can fix anything, and so I was on my way later that afternoon. Needless to say, I have a full set of tools and spare parts, ten gallons of water and food when I'm out in the middle of nowhere. But no spare gear shift lever - they never break!

 

Collecting hematite at the Baxter Mine outcrop on a cooler day. Most is mixed with limonite, so it takes some looking to find hematite that won't confuse a student.

 

 

 

July 15, 2017 by RC de Mordaigle
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