Materials are the resources used in Fabrication. There are four types of materials: Organic, Mineral, Synthetic, and Exotic. They come in fragments (0.99 or less) or blocks (1.00 or more).
Materials can sometimes be found as loot, but more often they must be produced at a Recycler from other items, like Junk.
Mineral materials are derived from ore found on Earth such as iron, copper, or tin. Junk items tend to provide Mineral materials the most frequently, and drink items always provide some (presumably due to their aluminum and glass containers).
Synthetic materials are derived from plastics or other man-made substances created in a factory. Most food and drink and junk items provide Synthetic materials, though in relatively small concentrations.
Exotic materials are derived from the Typhon ecosystem. Typhon-derived junk items tend to provide the most Typhon materials.