I whipped these up for Newbie DM after a comment he made about a lack of lava-based tiles. Just print these off, then cut and assemble the stone tiles so the non-elementals will have something to stand on. Borders are provided to give a slightly more natural transition between safety and instant death.
They are 300 dpi print-quality. The squares are the standard 1" that Dungeon Tiles use, so they'll work with your minis.
Get the images here (5.7 MB .zip, Medifire)
Feedback and suggestions on other useful sets/textures are welcome.