are laccolith, lobolith, dikes and sills formed of porphyritic texture?
Laccoliths, lopoliths, dikes and sills are all characteristic modes of occurrence of hypabyssal rocks, generally small in scale compared to most magma chambers. They are magmas which have cooled in a near-surface environment. None of these terms necessarily implies a particular petrologic texture. So, for example a dike or sill may be aphanitic, porphyritic, aplitic, pegmatitic or even glassy obsidian - and other less common textures. Nevertheless, many hypabyssal rocks are porphyritic. All this means is that the magma crystallized in two stages. The first stage was deeper and slower cooling, allowing some crystals to grow, sometimes to much larger size than the rest of the crystalline matrix. The second stage is when the magma is intruded at shallow depth, resulting in much more rapid crystallization of the remaining melt. Hence the porphyritic texture of large crystalls within a fine-grained matrix.