GEOL 1301 Lab 3

GEOL 1301 Lab 03 Igneous Rocks Igneous rocks form from magma, lava, or pyroclastic material and are classified according to their composition and texture. Your lab instructor will review some of the common igneous rocks, their formation mechanisms, and the terms mentioned in these instructions. Lists of textures and adjectives used to describe the overall composition of igneous rocks can be found below, as well as links to rock identification keys. Please complete the worksheet (“Examining and Classifying Igneous Rocks”), then upload your completed lab on Canvas. Textures: • • • • • • Phaneritic Aphanitic Porphyritic Glassy Pyroclastic/fragmental Vesicular/frothy Composition/Grayscale: • • • Felsic (light) Intermediate (between light and dark) Mafic (dark) Identification Key: See http://geology.about.com/od/rocks/a/Rock-Tables.htm Examining and Classifying Igneous Rocks Use the following link to identify the igneous rock samples listed in the table: http://profharwood.x10host.com/GEOL101/Labs/Igneous/index.htm Sample Number 1 2 4 5 7 9 10 12 Texture Composition/ Grayscale Other Observations (Visible Minerals, Special Features, … Rock Name Origin (How did the rock form?)