A system and a computer implemented method for performing simultaneous petrophysical analysis for composition and texture of a rock formation. The method includes inputting a set of response equations for sand, shale and fluid that are present in the rock formation, wherein the shale comprises laminated shale, dispersed shale and structural shale; determining simultaneously a solution of the set of response equations, the solution describing composition and texture of the rock formation; and determining from the solution volume fractions for sand, shale and fluid and a texture of the shale including fractions of laminated shale, dispersed shale and structural shale.