Abstract: A polymer masonry unit (PMU) and methods and systems for forming PMUs are presented. In embodiments, a PMU may be made from a PMU mixture of a polymer, a quarry byproduct, such as a limestone aggregate, and water. The PMU may be ambient-dried to become a brick unit. The proportions of the PMU mixture may include 1-10% polymer, 80-90% quarry byproduct, and 1-10% water. The process for making a brick using the PMU of embodiments may avoid a kiln-firing process, which is costly, creates waste, and consumes significant energy. Furthermore, the PMU mixture may be formulated to enable the PMU mixture to be extruded from an extruder, enabling a system for making bricks to take advantage of the extrusion method, which can be very efficient and cost-effective for making bricks, and which is currently not possible with existing techniques and systems.