@woodland creature :pleroma_fox_tan: no, I annealed in vermiculite hoping it would be easier to drill, but it had no effect. I got it from a scrap yard that has an assortment of dimensional stock from project overages, so presumably it's all mild steel or at most a36. This was in a pile of about 100 sticks. 

 @Hypnotize Feminists vermiculite has a fair amount of air vs sand? you may need to do it in a more controlled ramp with a furnace  

i was able to temper A2 to a blue color and it worked when i was making a tool. can't recall exactly what the project was off hand 

 @woodland creature :pleroma_fox_tan: yes I believe so. The particles are almost the size of kitty litter but they have the weight of styrofoam, so very low density. That being said, if I put in a piece of iron it's still too hot to touch nearly 6 hours later, so the insulation value is excellent.

https://media.clubcyberia.co/pleroma/e80759ce7ca114fa53719574bb7e98d27a6df8e0cdaa2c832cfc103083e0b587.jpg 

 @Hypnotize Feminists good to know