So this is what happened: My manual crucible setup uses a Dense Invar Burning Box and a Ceramic Crucible. I threw in 16 Blue Sapphires into the crucible, it filled up the crucible, then I turned on the burning box and it started heating up slowly. The temperature was approaching the melting point, around this time I turned my back for a few seconds to take a sip of my drink. Next thing I know, the crucible's empty and the thermometer's reading 2400 K. Oops.
Because most stuff in GT6 is (or can be) automated, and because a lot of processes take
a very long time, it rarely makes sense to pause the game when tabbing into another
window, making a drink, or going to the bathroom, etc. Instead, I simply press "E" to bring
up the inventory and free the mouse pointer, alt-tab out of the game and leave it running in
the background. However... since these are all occasions where I would normally pause any
other game, on some level my brain registers this act as pausing. On more than one occasion
I've returned to find a death screen, the contents of my inventory strewn across the map, and
either: a) a horde of mobs under a night sky; or b) a fiery void where my crucible used to be....