PG_7103_L04_IgneousRocks

PRE-LAB QUESTIONS 1. Which of the following are mafic minerals? (Select all that apply) a. Quartz b. Pyroxene c. Plagioclase d. Olivine 2. Rocks that cool quickly have ___ crystals. 3. Rocks that cool slowly have ___ crystals. 4. True or False? Rocks formed from volcanic eruptions are an example of extrusive igneous rocks. 5. What textures are possible in intrusive rocks? (List all that apply.) 6. What textures are possible in extrusive rocks? (List all that apply.) ©2016, eScience Labs Igneous Rocks

EXERCISE 1 DATA SHEET Table 3. Salol Crystallization Environment Observations Dry Styrofoam® Cup ● mixture started to melt the bottom of the styrofoam cup when initially poured ● slow formation of crystals ● transparent coloring ● big crystals ● phaneritic Styrofoam® Cup with an Ice Cube  ● formation of crystals began almost immediately when poured with the ice cube ● opaque coloring ● small crystals ● aphanitic ©2016, eScience Labs Igneous Rocks

EXERCISE 2 DATA SHEET Table 5. Igneous Rock Identification Sample Letter Color Mafic Color Index Minerals Present Texture Rock Name A medium-light gray intermediate quartz, potassium feldspar, plagioclase, biotite, amphibole aphanitic andesite B light brown with black specks felsic quartz, muscovite, feldspar, plagioclase, biotite, amphibole aphanitic rhyolite C light gray with black and white specks felsic quartz, plagioclase, biotite phaneritic granite D dark brown mafic feldspar, plagioclase, amphibole, pyroxene, olivine vesicular scoria E glossy black with gray specks felsic, intermediate, mafic quartz glassy obsidian F dark gray, with light gray and metallic specks mafic quartz, muscovite, plagioclase, feldspar, biotite, amphibole aphanitic basalt ©2016, eScience Labs Igneous Rocks

EXERCISE 2 POST-LAB QUESTIONS Check all the boxes that apply to each of the samples: Table 6. Sample Textures and Compositions Sample Letter Intrusive Extrusive Mafic Felsic Intermediate A x x B x x C x x D x x E x x F x x ©2016, eScience Labs Igneous Rocks