Fluid Interactions add Fluids and its related interactions with Water and Lava.
It implements a form of in-world processing. For example, raw metal blocks melts into its fluid when placed adjacent to a Lava Source. And those custom fluids then solidifies when placed adjacent to a Water Source.
The mod adds vanilla materials and a few common modded metals. Aside from metals, it also include interaction to transform sand into glass, and melt quartz and a few others.