Flint slabs

[Bluesky78987]

Those are really pretty! Especially with those quartz veins, but even without!

[accidentalrockhound]

Super nice slabs. Try to heat a piece not a lot. Maybe cut a couple more feom a different piece and heat that ? Just a thought.

[1dave]

Who would waste time with flint?

ME!

[jamesp]

If you do decide to heat them I would keep it below 600F. Assuming that is Flint Ridge. Sure is pretty as is....
Maybe 525 or 550F. Maybe as low as 500F.
Flint ridge can go way red at 600F. Making it monotone red and boring.

First and last time heating flint ridge with a load of metal salt rich yellow coral at 600-615F. Ruined it, too hot, too red, too brittle
started out yellows and almost oranges.




Whereas the coral was spot on, a bit too hot for some of it as some were too brittle

Before. small corals sitting on pea gravel for size reference.



After heat and hammer broken. Colors imply 600F +. Color is accurate temp gauge for a given stone.



More before and afters of this batch of coral. From a short stretch on the Suwannee River that always heat treats to exotic colors.
Probably high iron content. It's full of something. 2nd collecting trip to this spot:

www.flickr.com/photos/67205364@N06/32651722950/in/album-72157686710708022/lightbox/

Same drab yellow coral from same 1/4 mile stretch of Suwannee. First collecting trip.
Parked truck at bridge and quicky sample collected in river on way to collecting another collecting spot.
The first 18 photos after heat from this spot. Some of the most drastic coral changes ever.

www.flickr.com/photos/67205364@N06/15090620701/in/album-72157646653965727/

[Luminin]

Wow! Great info and images there jamesp! I think the red is pretty, but brittle is brittle :/

[jamesp]

Oct 29, 2017 20:21:43 GMT -5 Luminin said:

Wow! Great info and images there jamesp! I think the red is pretty, but brittle is brittle :/

That flintridge may have heated to red before it became brittle luminin.

You can easily do a heat treat test by digging a 5 inch deep hole and breaking up the soil.
Bury your flint ridge at various depths from 2 to 5 inches deep covering them w/soil as you refill the hole with the dug soil.
Build a wood fire on top on a calm no-wind day. Keeping it fueled occasionally for about 8-10 hours.
Let it go out and let the coals burn out which may take a 1 to 3 days.
After everything has cooled down dig up your flint ridge and look at the color profile and brittleness from 2 to 5 inches of depth.
A raw method but cheap and revealing. Native man did it that way. Guessing he knew the heat derived colors that made the strongest spearheads and optimum workability.

Or find surface flint ridge that experienced a forest fire. Could be an ancient forest fire.
Dig around or find disturbed areas like plowed ground. Observe colors.

Many of these Savannah River bryozoan cherts were heat treated by a recent or ancient forest fire(s). Chert vein is close to surface for many square miles.

Natural color unheated:



Heated, note reds and greens, oranges, they are only from heat

www.flickr.com/photos/67205364@N06/8397817577/in/album-72157632569773602/

[MsAli]

Beautiful just the way they are. Love the "ghost"