A novel sustainable material was developed using a mineral waste as filler for polymeric composites. Soapstone is a mineral typically found in abundance in communities that rely heavily on artisanal crafts as a source of income and which are often in a situation of social vulnerability. Rock recovery in those activities is low and the waste disposal is done with little control, which can be hazardous to the environment and the health of the local residents. Thus, to use this residue to reinforce the properties of a polymer with a wide range of applications, such as polyethylene, can lead to positive economical, social and environmental returns. A thorough characterization of the residue was done with automated image analysis, Xray diffraction, infrared, and Raman spectroscopy. The waste particles were incorporated into a high-density polyethylene (HDPE) matrix in three compositions: 10, 20 and 30 wt percent. X-ray microtomography was used to quantify the filler volume fraction, void content, and the microstructural homogeneity of the composites. It was found that the soapstone particles have a strong tendency of forming clusters in the HDPE matrix, however, statistical analysis revealed that the volumetric filler distribution was homogeneous throughout the samples. Rheological, tensile and creep tests assessed the influence of the particles on the polymer s processing conditions and practical mechanical behavior. A relevant increase in viscosity and shear stress was observed at lower shear rates for higher filler loadings. The addition of soapstone waste particles successfully decreased creep strain and increased both yield strength and elastic modulus of HDPE. However, the incorporation of higher amounts of filler altered the fracture mechanism and considerably decreased ductility and creep rupture time of the polymer. The relationship between the microstructure and the macroscopic mechanical behavior was investigated by fitting tensile test data with macro-mechanical models from the literature, which allowed the quantification of the interfacial bonding.