In "Facade" (The Sandman #20), Element Girl dies after a conversation with Death of the Endless (and possibly with Ra as well). Below is an image of her death (borrowed from another post on this site, courtesy of Gallifreyan):
Rainie finishes her (pseudo?) conversation with Ra, becomes a whitish statue, and crumbles into a heap of white grains on the floor:
What happened to her body, chemically? In earlier panels of this issue, she seems to transform her body into real chemicals for various uses (eg magnesium1 to blow a door open, nitrogen gas to escape her clothes); is there any evidence (within the universe or without) as to what happened to Element girl on a chemical level?
1 Sodium may have been a better choice; however, I understand that it's likely that the writers chose an element that more non-scientists would associate with flashy explosions -- I assume many people would simply be confused by a reference to "half of table salt" when Element Girl breaches the door. (But see also "Don't Flush Sodium Down The Toilet.")