Found this the other day, I collect all stones and tools, so I thought this stuff was pretty neat. Quite sure its not any kind of fire rock. It leaves a powder residue on anything it touches.

Yeah, thats as good an example as it comes..
Too bad it fell out of the guys paint box, he could have used it for a great cave pic

Well I scraped up some powder and added some water and tried my hand at cave painting!!
I read the ancient ones added animal fat and or blood to the mix for a longer lasting mark. (several thousand years) Maybe valspar needs to check ingredients!

EXCELLENT technical report ( and really neat cave figures )
I like the animal fat idea since it might take months to completely dry and that would allow time to work
it's way into the cave wall surface for extra longevity.

Now I know why some cave paintings are on the ceiling or pretty high.......
To keep the racoons from licking the fat off

hey that's pretty cool. thanks for the demonstration.