what distinguishes the two main types of igneous rocks
Rockhound. Igneous rocks are classified as either extrusive or intrusive. Extrusive rocks form from lava at or above the ground, and intrusive rocks form from magma below the ground. Granite is intrusive, pumice is extrusive.he two types of igneous rock are are intrusive and extrusive, depending on where they form. Intrusive igneous rock forms underground from slow cooling magma. Extrusive igneou â¦ s rock forms at or near the surface from quick cooling lava. 1 person found this useful. Paul Jones. Rockhound.