Point Cooked in Fire

[Charl]

Found this little guy in a field yesterday. In the nick of time with still another snowstorm Tues-Wed. this week. It shows a fire pop on the edge of one side(2nd photo, right edge), appears more brittle then normal, and there is damage at the base exposing a desiccated reddened interior. Much redder then the camera shows for some reason. Anyway, quite possibly this is a point that was cooked inside the game it brought down. Leading to scenarios like this: "Dinners ready! Watch your teeth, couldn't find the point". Lol......

 

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[larson1951]

i have agree with you on that charl....................'wayute....okati shakowin(ooo-cha-tee sha-ko-wee)........hoka hey!

 

[joshuaream]

I've wondered about that scenario before, and I'm not sure if a cooking fire is really going to get hot enough long enough to thermally alter & damage a rock.

When knappers heat treat stone, they are usually dealing with 400+ degree temps for multiple hours (10 hours, 36 hours, even 72 hours for some types of materials.) Some things like novaculite are cooked at temps up to 900 degrees. Not many edible foods can withstand or need that much cooking at high temps. From my limited knapping understanding, fire pops happen when the temp rises too quickly, gets too hot, or the rock has a lot of moisture in it (and temp rises too quickly.)

I don't think anything near those temps would happen lodged in a piece of juicy meat. In fact, if there are any bbq fans out there, they should be familiar with the stall/plateau that happens in big cuts of meat cooked over a fire or in a smoker. You can toss a big pork butt or brisket over the fire, and at about 150 to 160 degrees the temp just stalls for hours and nothing gets hotter. A good 5-8 hours later the temps might get to 190 degrees.

I could see pieces falling out in the fire, or a forest fire damaging pieces if they were on or near the surface.

 

[Harry Pristis]

For example, Purdy says that the critical temp needed to alter Florida cherts is about 350C (662F). This is the temp which produces eutectic development (fusing the surface of quartz microcrystals, using impurities in the crystalline structure as flux). (Full vitrification - turning microcrystalline quartz into noncrystalline quartz - requires much, much higher temps.)

Purdy does note, however, that a color change occurs at between 240C (464F) and 260C (500F) if minute amounts of iron are present. The color change is not synchronous with the vitreous change that occurs at 350C.

 

[Charl]

Sure, maybe just tossed in the fire rather then cooked in the meat. I could tell it was in a fire as soon as I picked it up even though I've never seen a point made of the material before. I thought it might actually be too brittle to clean at first, but not the case...