Pondering Petrified Wood

Human beings are funny creatures. When we see something, we immediately want to categorize it.  For a birder, identifying and tallying species is a huge part of the hobby. For my work as a scientist working with satellite imagery, my task is to categorize the types of land cover (cropland, urban, deciduous forest, etc.) on the earth’s surface.  For a rockhound?  I’m struggling with identification as a rockhound newbie, just as I did 20 years ago when I was a birding newbie.

Petrified wood is one category of material I thought was easy to identify. When I’m out on the Buffalo Gap National Grasslands, there is a LOT of petrified wood lying around. By that, I mean there’s a lot of easily identifiable pieces that look exactly LIKE wood, with obvious grain patterns.  But as with anything in life, it’s not that easy.  Below are some of the obvious, and not so obvious pieces I’ve found on the Grasslands. Thoughts? Are all of these petrified wood?

Petrified Wood - Buffalo Gap National Grasslands, South Dakota

First, an obvious piece of petrified wood. This is what I find the most of…gray exterior pieces with clear grain patterns, some of which are so detailed they look like fresh pieces of wood.

Petrified Wood - Buffalo Gap National Grasslands, South Dakota

Another obvious one. Both of these first two pieces have also been tumble polished to a nice shine.

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

And this piece? This is the most colorful piece I’ve found, for something that’s possibly petrified wood. You certainly see a linear “grain” running throughout. Petrified wood? Perhaps an agatized petrified wood?

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

Same piece as above, except on the flip side. Again, you see the grain pattern throughout.

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

A less obvious one. The photo doesn’t show it as clearly as what you see through a loupe, but there are rough “grain” patterns. They’re more little streaky nodules all oriented the same direction. I know there’s petrified palm that can be found in this area, but I don’t know what exactly the palm looks like from this area.

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

A similar one, with little linear nodules lined up in the same orientation like a wood grain (again, a bit hard to see in this photo).

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

The photo of this piece does a better job showing the type of “grain” seen in the previous two pieces as well. Obvious, and all oriented in the same direction.

More South Dakota Agates

On Labor Day I again made the long trek to the Buffalo Gap National Grasslands of western South Dakota, a day to look for agates, fossils, petrified wood, and other goodies.  For the first time since we discovered rockhounding this summer, there were actually a number of other people out searching.  You can see how the known agate hunting locations would get picked over.  However, it’s quite similar to a visit to a busy national park like Yellowstone or Yosemite…just get away from the road a bit and you’re likely to have it all to yourself.

Despite several other searchers, I was able to find solitude just by hiking back away from the gravel roads in the area.  There’s no doubt there are more and better finds as you get away from the roads and places people park.  An interesting day, marked by a heavy haze all day from western US forest fires, but also a day filled with agates.  Here are a few agates from the day. Also the latest batch that’s gone through my polishing.  I’ve pretty much got it down now, and can get a real deep shine, but it’s a 2-month process from start to finish!  Always good to finish a batch and see what you get for all your hard work.

Fairburn Agate - South Dakota

This is one I would have loved to have found before it had worn down. I do think this is a legitimate Fairburn agate, but some of the bands are worn away in places. In others, you can really see the fine detail.

Fairburn Agate - South Dakota

The flip side of the same Fairburn. I think I’m going to call this one the “Bacon” agate, given the banding on this side.

Polished South Dakota jaspers and agates

The latest batch to finish in my small tumble polisher. I’m having much better luck now in getting a great shine, simply by 1) taking twice as much time, meaning 2-full weeks in each of the 4 polishing stages, and 2) using distilled water instead of our very hard city water. Just the choice of water has made a huge difference in the shine.

Agatized Syringopora Coral - Fossil

A piece I found earlier this summer that just made it through the polishing process. This is an agatized piece with bits of Syringopora coral fossils throughout. A unique and gorgeous little piece.

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