The engineering properties of a rock are much dependent on the microscopic features of the minerals comprising the rock. The physical and mechanical features of various minerals(i.e. quartz, biotite and albite) in Beishan granite are investigated in a micro scale in the current study. The microscopic physical features of the minerals are characterized by volume and density, while the microscopic mechanical features of the minerals are characterized by Young modulus and Poisson ratio. The open database is used to obtain the initial crystal structure, initial cell parameters, and the unit and super cells of the minerals. The stable configurations of the mineral cells are obtained using the geometry optimization. The microscopic physical and mechanical parameters of the stable configurations are then computed using the molecular mechanics simulation. The effects of temperature and pressure on these microscopic physical and mechanical parameters are furthermore examined using the molecular dynamics simulation. It shows that in the main minerals included in granite, the great-small sequence of the cell volume is albite, biotite, and quartz, while that of the cell density is biotite, quartz, and albite. The Young modulus values of quartz, biotite and albite are 161.70 to 168.78GPa, 164.85 to 579.93GPa and 110.72 to 112.49GPa, respectively. The Poisson ratio values of quartz, biotite and albite are 0.25, 0.16 to 0.31, and 0.27,respectively. When the temperature changes from 300K to 500K under the pressure of 100kPa, the volume increases 0.17% and the density decreases 0.15%with no obvious changes in the Young modulus and Poisson's ratio for the quartz cell; the volume increases 0.24% and the density decreases 0.26%with the Young modulus increased 140.55% and the Poisson's ratio decreased 26.92%for the biotite cell; and the volume decreases 3.76% and the density increases 3.91%with the Young modulus increased 319.71% and the Poisson's ratio decreased 7.41%for the albite cell. When the pressure changes from 0.010 to 0.020GPa at the temperature of 298 K,the volume, density, Young modulus and Poisson's ratio have no obvious changes for the quartz cell; the volume and density have no obvious changes with the Young modulus increased 53.79% and the Poisson's ratio decreased 23.81%for the biotite cell; and the volume and density have no obvious changes with the Young modulus decreased 36.24% and the Poisson's ratio increased 29.41%for the albite cell. These theoretical results can be referable in analyzing the macroscopic physical and mechanical properties of the rock materials in a micro scale.
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