There is provided a method of fabricating a composite material (114), the method comprising providing (102) borehole solids (101) originating from a borehole in the earth and embedding the borehole solids (106) in a base material (110) thereby forming the composite material (114), wherein the base material (110) comprises a polymer. According to an embodiment, the borehole solids (101, 106) contain oil, e.g. on a surface thereof. The oil containing borehole solids (101) may be preprocessed (104) before embedding or may be directly embedded in the base material (110) without preprocessing. Such embodiments allow for a recycling of oil contaminated borehole solids (101, 106) while providing a resource for a filler for polymers.