1. IGNEOUS ROCKS by Charina Cameron Part 1: Classification & Composition

2. CLASSIFICATION Based on –Composition Magma type –Felsic = granitic –mafic = basaltic Minerals present –quartz, K-feldspar, plagioclase, mafic minerals, etc. –Texture Reflects magma cooling and crystallization history Finely crystalline is usually volcanic Coarsely crystalline is usually intrusive –Place of origin Plutonic or intrusive Volcanic or extrusive

3. PLUTONIC vs VOLCANIC Volcanic igneous rocks (extrusives): –rhyoliteandesitebasalt Plutonic igneous rocks (intrusives): –granitedioritegabbro

4. GRANITE Felsic magma Quartz Muscovite Biotite Hornblende Orthoclase

5. DIORITE Intermediate magma Pyroxene

6. GABBRO Mafic magma Pyroxene OlivinePlagioclase

7. ULTRAMAFIC ROCKS Dunite Peridotite Pyroxenite Amphibolite (Hornblende)

8. PEGMATITES Coarse textures (phaneritic) Usually granitic in composition Crystallized from hot residual fluids from magma May contain –very large crystals –unusual minerals

9. SOME PEGMATITE MINERALS Quartz & Orthoclase Biotite, Quartz, & Orthoclase Tourmaline crystals (black) in Orthoclase

10. SILICA CONTENT OF MAGMAS Silica is SiO 2 Refers to Si and O found in silicate minerals

11. PROPERTIES OF MAGMAS

12. BOWEN'S REACTION SERIES 2 branches: –Discontinuous –Continuous Residuals: –K-feldspar (orthoclase) –Muscovite –Quartz