Large mineral fillers have long been used in papermaking for many reasons. The finish of the writing and printing paper depends on using the fillers as internal or surface treatments. During this study, Tamarisk sp. and Prunus amygdalus pulp-filled papers with raw phosphogypsum (PG) and calcined PG (CPG) at different percentages were studied. First, the prepared minerals (treated and untreated ones) were characterized by different analytical methods such as SEM and EDS. Subsequently, different handsheets with a basis weight 60 g−2 were prepared on a Rapid Khöten sheet former following the standard method. The added amounts of PG and CPG fillers were included from 0% to 15% based on the pulp. The effects of incorporation as well as the quality fillers into physical and optical properties were assessed. It can be deduced that the incorporation of CPG at 800 °C improved filler retention by as high as 92%, and the optical properties of the filled paper was strikingly enhanced, while the strength properties were practically negatively influenced. It was clear that calcinationstepsreduce the fiber–filler–fiber bond. Thus, results are in accordance with the SEM observation, which confirmed the obtained physical properties.