Obsidian cutting tools

I read an interesting article in the New York Times that discussed the obsidian outcrops in Yellowstone National Park, and how they were mined for hundreds to thousands of years to supply the cutting tools used by the First Nations tribes of North America. This got me thinking about the good ol’ days of my wayward youth…

Having spent far too many years bullying our way through the brush-choked mountains of the Pacific Northwest, the field crews I’ve worked with have become all too familiar with those tools that can (and did) chop down whatever would get in our way.

Much of this time was spent cutting straight lines through the forest — putting in “survey grids” in preparation for the geochemical and geophysical studies that were a necessary step in the early stages of exploration for the valuable metals that we all need and demand. We used a variety of cutting instruments, ranging from bow saws to chainsaws to machetes. I even worked with one crazy old man in the 70s whose favorite tool was a double-bit axe (it’s scary to realize that I’m now older than he was at the time).

Unfortunately, along with cutting the brush came the inevitable misses and slips, leading to the unfortunate extracurricular damage that would be inflicted by the tool of the day on the fool of the day.

We learned early on that while a machete slice can be deep and ever so painful, there’s generally no way to cover a chainsaw cut with a Band-Aid. In large measure this is the result of the width of the cutting edge: a chainsaw simply damages more skin and muscle cells than does the much narrower machete — sure, it’s a really big knife, but the blade is only a fraction of an inch wide. Given a choice, we usually voted to use machetes for just this reason.

Now consider the difference between a machete and a surgeon’s razor-sharp scalpel — it’s even thinner and damages a much narrower swath of cells as it’s doing the cutting. As such, doctors use scalpels for surgery, as opposed to machetes (or chainsaws). This makes abundant sense, and helps explain why many surgical wounds close and heal in a matter of days, as opposed to the month it took for Bob’s chainsaw-cut leg wound to support his weight and let him get back in the field.

But no matter how carefully you sharpen a steel blade or scalpel, if you look at it under a microscope the cutting edge still looks like a brick!

Not so with obsidian. Obsidian is a naturally formed volcanic glass that breaks with what is call a “conchoidal” fracture — just like the curved breaks you get when you shoot a BB through a plate-glass window. This unique breakage pattern is controlled at the atomic level, and makes for some very sharp cutting edges — while a steel scalpel cuts through (and destroys) skin and/or muscle cells (as well as several hundred on both sides), obsidian cuts between the cells, and does very little damage to the surrounding tissue.

I have taken countless students on field trips to the obsidian fields of eastern Oregon and northern California. One of the important safety tips we always cover is the need to be careful — this stuff can slice your hands (and/or any other part of you that gets in the way) both quick and deep. Sadly — and no matter how well and meticulously the kids pay attention — there are ALWAYS cuts, with the inevitable shrieks and screams of betrayal that accompany them. (Stock in the companies that supply Band-Aids probably goes up whenever I schedule one of these classes into the outback!)

But it’s weird: no matter how many students get wounded, most of the cuts are nearly healed by the following morning. This should come as no surprise, however: since the business end of an obsidian flake is only one atom wide, it cuts between the cells and not through them like a steel blade does, and results in much less damage to the surrounding tissue. This allows for much quicker healing. (I doubt this gave much solace to General Custer, or any others — of any nationality — who have been impaled by an obsidian arrowhead.)

Anyway, so why not use obsidian scalpels for all surgical procedures? Once again, the answer is simple (don’t you just love the simplicity of the earth and its processes?): The same brittle glass-like atomic structure that made it possible for ancient peoples to fashion arrowheads — and other “primitive” cutting tools — results in the possibility of small flakes of obsidian breaking off whenever a bone or other hard object is hit. This could leave microscopic (or larger) flakes of obsidian in the wound.

That would be bad!

As a result (and looking beyond the archaic attempts of the First Nations peoples), obsidian scalpels are used in those surgeries where a clean cut with limited damage to surrounding tissue is required, and where there are few, if any, bones in the area. Two obvious examples jump to mind: the brain and the eye. (Note: modern-day laser surgery is somewhat changing this, or so I am told.)

In any event, check out the obsidian fields in Newberry Caldera near Bend, Oregon, Glass Mountain near Medicine Lake in northern California, or any of the obsidian outcrops south of Mono Lake in the eastern Sierra Nevada. You won’t regret it… but be sure to take along a good pair of leather gloves (and a box of Band-Aids).