In this study, we investigated the mineralogical, physical, and mechanical strength properties of Şevketiye granite (Lapseki), Kestanbol granite (Ezine), and Yassıbağ granite (Bayramiç) rocks found in the Biga peninsula. The rocks are mainly composed of quartz monzodiorite (Şevketiye and Yassıbağ) and quartz monzonite (Kestanbol), predominantly consisting of feldspar (plagioclase and alkali feldspar), quartz, mafic minerals (biotite and amphibole), accessory minerals (sphene, zircon, and opaque minerals), as well as secondary minerals such as sericite, epidote, and chlorite, which have a similar mineral composition. In this study, various physical properties such as water absorption and porosity, as well as mechanical properties including uniaxial compressive strength, tensile strength, Schmidt hardness tests, Los Angeles abrasion, and freezing resistance test with sodium sulfate (Na2SO4), were determined for granitic rocks. The test results determined the influence of petrographic features, including mineralogical compositions, texture, and alteration, on the mechanical strength of the granite rocks.