IGNEOUS ROCK IDENTIFICATION ASSIGNMENT #2B (40 pts)

Igneous Rocks

Igneous rocks are made up of intergrown mineral crystals formed by the cooling and solidification of magma or lava. Igneous rocks are classified on the basis of their mineral composition (felsic, intermediate, mafic or ultramafic) and texture (aphanitic, phaneritic, porphyritic, glassy, vesicular or pyroclastic). The composition gives information about the type of magma from which it formed. Generally, more felsic minerals are lighter in color, including pink, while more mafic minerals are darker in color, including green. The texture provides insight into the cooling history of the magma. Coarse grained rocks are ones that individual minerals are visible to the naked eye, cooling very slowly beneath the Earth’s surface. Fine grained rocks contain minerals too small to be seen with the naked eye, cooling at the4 Earth’s surface very quickly. Use the information from igneous rock classification chart below to identify the ten unknown igneous rock names (granite, basalt, gabbro, diorite, rhyolite, tuff, scoria, andesite porphyry, peridotite and obsidian). Use sections 5.1, 5.2 and 5.3 in the textbook for assistance.