Coke not burning?

[Solarjunkie]

I found a pile of coke in the garden which must have been there for over 30 years. Never one to turn my nose up at free fuel, I put a couple of pieces on my woodstove, which generaly seems quite happy to burn anything I put in it, including the odd piece of coal.
But the coke has been in there two days and has not burnt. I took the lump out, glowing red, and left it outside to cool - it looks the same as when it went in!
I'm puzzled - coke used to be a common fuel, why doesn't it burn?

[bobjugs12]

You'll find that it's probably down to the container? Is it an old glass bottle, a plastic one or a can.

Try pepsi for a better heat.

Glad i could help.

[buildersmate]

It isn't coke - it is clinker - the waste product from out of the fire. Somebody nabbed you to the carbon content of the material 30 years ago.
Use it on the ice/snow next time around - provides a great grip.

[Solarjunkie]

Some of the pieces are a big as a football, I have never seen clinker that big!