White petrified wood point

I bought this piece of rock at the maple ridge rock club. It’s a great slab of some even better material. I think it may be opalised wood from Nevada. It’s the only place that I’ve ever seen a stone like that come from. If I had to guess I would say it came from McDermit nevada.

This one’s for sale here, if you’re interested: it’s 35 bucks

Categories: arrowheads, flint knapping, rock hounding, USA | Tags: , , , , , , , , , | Leave a comment

Flintknapping Obsidian.

The formation of obsidian is a highly debated subject. The main issue lacking consensus is the composition of the lava. The average flintknapper believes that obsidian was formed from lava that was over 80 percent “silica” (SiO3) cooling rapidly on the surface. The rate of cooling is correct but geologists say that the lava would have had to cool in an ocean, not the surface, in order for the lava to cool quickly enough. Geologists also say that the composition of Obsidian is chemically identical to that of granite and rhyolite, crystals formed from slow cooling deep within the earth.

This is not the only theory on chemical composition that I have heard, though. Some say that basalt has the same composition as obsidian and granite. We know basalt is a primarily mafic (melted oceanic crust) lava, while granite is formed from felsic (melted continental crust) lava. These parallel contradictory theories, both taught in schools and readily available on the internet, are the root of the confusion we the flintknappers face.

Here’s one of my theories. Obsidian was molten rock… and came up to the surface in a way similar to basalt. The lava had a relatively low silica content (less than 50%) since lavas that have high silica content are much more volatile and tend to make extremely explosive volcanoes. Lava flowed out of the shield volcano underwater, cooling the stone almost instantly without allowing any air to enter the obsidian.

The composition of the lava doesn’t matter because the cooling action would be the same as the process for slag glass. Slag glass formed from the rapid cooling of a molten random rock mixture. If anything molten cools fast enough, you can get it to form a conchiodial fracture. This can be seen whenever a cheaply made cast iron pot is dropped, since they will occasionally chip.

However the stuff is formed, there’s one thing we can all agree on: you can make some awesome stone tools out of it!

Categories: flint knapping, rock hounding, USA | Tags: , , , , , , | 1 Comment

Silicified mud-stone

This stuff is sweet. I love it. Apparently it’s a mud-stone that lithified or agatised, after a bit of heat the rock slicks up and works beautifully.

But then again, I’m a sucker for the brown rocks.

This material comes from the Columbia River Gorge..  and a fat lot of good that does anyone trying to find it..  The gorge runs for miles and miles with very few access points. The best way that I can figure for you to explore the area is to get yourself a boat and hug the shoreline looking for river bars that you can search for knappables. I know of knappable stone that comes from the Deschutes area and from Biggs. Other than that i have no idea. I went to the gorge at the access point near George Washington, (the town.. not the guy) and I found a few pieces of different coloured opalites.. but they were few and far between, with the source of the rock potentially anywhere along the cliffs of the gorge. Good luck to any of you trying to find rock. If you find some sources and are willing to help a brother out, let me know! haha.

But i digress..  Here’s my arrowhead

Categories: arrowheads, flint knapping, rock hounding, USA | Tags: , , , , , , , , , , , , , , | Leave a comment

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