29 slide PowerPoint on igneous rocks. See preview! Starting with the rock cycle, the PowerPoint focuses on igneous rocks and how to identify them based on the following properties: formation environment (intrusive versus extrusive), crystal habit, texture (coarse, fine, or glassy), mineral composition, and color. Rocks addressed are granite, basalt, gabbro, rhyolite, obsidian, pumice, diabase/diorite, and scoria.The PowerPoint ends with a concept map graphic organizer and summary page. This