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Here's an unusual bit of petrified wood. This is from the Nacimiento Mine near Cuba, New Mexico. The mine has been closed for some time but occasionally collectors are allowed in. (The land has reverted to the Forest Service, which is cleaning up the aftermath of an abortive attempt to extract copper using sulfuric acid leaching.) The mine is a huge point bar deposit of wood in the Shinarump Formation (Triassic) that was permineralized with copper minerals. The black here is mostly chalcocite, copper sulfide, which in a few spots has been oxidized to blue or green azurite or hematite. At the mine itself, you see black fragments of the chalcocite-mineralized wood with lots of blue-green staining around it, as well as occasional wood fragments that were silicified rather than copper mineralized. At left is a chunk that was permineralized with copper; at right is a twig that is more conventional silica permineralization. The difference seems to be in the original state of the wood. It appears much of the wood was partially burned, and the charcoal was more likely to permineralize with copper minerals than silica. Cool as copper permineralization is, the fact that it's charcoal rather than pristine wood means this is of more mineralogical interest than paleontological. Still, though y'all might enjoy.

Now that the weather has officially snowed me in. I’ve gotten around to posting some trips I took during the summer. At request of my friend, I won’t reveal the exact location of this area but if you know where this is you know there’s abundant petrified wood. I can say it’s close to Capitol Reef National Park (definitely not in the park ). Here’s the stratigraphic column for the area. The petrified wood we were looking for were in the Petrified Forest member and the Shinarump conglomerate member. The area is a long hike in. So even though we saw abundant wood, we could only take what we physically could carry for a couple miles with our camp gear.