(Cooked) common opal (some points, poor pic sorry)

[Zuma]

A cheap easy way to test for how much heat and time you may need on an unknown chert is ---
Put a few thin flakes in a cast fry pan and raise the heat a little at a time. Look for color change and test to see if there is improvement.  Safty glassed if you get it to pot lid temp. lol
Zuma

[Bryce]

I have some moss agate I was thinking about cooking. I might as well throw some of that opal in there.

[Zuma]

I have some moss agate I was thinking about cooking. I might as well throw some of that opal in there.

I have had good luck with Brazilian banded agate at jasper temps 450- 500.
Some of the more translucent material requires less heat and crazes at 500.
But you won't know if you don't go. Good luck
Zuma

[Bryce]

I got it cookin at 400 for 12hrs