Which rocks are generally formed by intruding magma

Sills are form when magma intrudes the rock layers, forming a horizontal or gently-dipping sheet of igneous rock

Thus, skarns are generally composed of minerals like calcite and dolomite, from the original carbonate rock, but contain abundant calcium and magnesium silicate minerals like andradite, grossularite, epidote, vesuvianite, diopside, and wollastonite that form by reaction of the original carbonate minerals with silica