Intrusive rocks are those which appear to have crystallized from magma emplaced in surrounding rock. As indicated by Figure 3.14 of Hamblin and Howard, extrusive rocks consist of rhyolite, andesite, and basalt. Your lab manual also explains various textures such as phaneritic , aphanitic , glassy , and pyroclastic . The classification of igneous rocks is based on the presence of absence of quartz, the composition of feldspars, the proportion of ferromagnesian minerals. Granite and rhyolite are called the felsic rocks, diorite and andesite are the intermediate rocks, and gabbro and basalt are the mafic rocks.
Plutonic rocks are igneous rocks formed at great depth.
A s tock is a small discordant pluton whereas a batholith is a pluton of more than 100 sq. A dike is a tabular body of igneous rock cutting across bedding and hence, discordant. A sill is a tabular body which is concordant. A blister shaped sill is called a laccolith . A pegmatite is a extremely coarse-grained igneous rock with crystals as large as 10 meters across.