Rock Identification Lab Question 1 Define Igneous Rock

Rock Identification Lab

Question 1 Define Igneous Rock • 1. Igneous rock forms when hot, liquid rock, or magma, cools and solidifies. P. 36

Question 2 How do igneous rock forms • Igneous rocks form when magma of different compositions cool at varying rates

Question 3 What are the 2 basic classification of igneous rock. • Intrusive igneous rock- Rock formed from the cooling and solidification of magma beneath the Earth’s surface • Extrusive igneous rock-Rock that forms as a result of volcanic activity at or near the Earth’s surface

Question 4 Describe how the chemical composition of the rock affects the color of the igneous rock - Light rocks/ Felsic- less dense contain more silicon, aluminum, potassium, and calcium -Dark rocks/ mafic- more dense contain calcium, iron, magnesium and poor in silicon

Question 5 How can you tell how long it took an igneous rock to cool, • An igneous rock that has cooled at a very fast rate has little or no crystals, and is often times smooth or is fine grained. • An igneous rock that has cooled at a slow rate has large crystals or is coarse grained.

Question six • See website http: //geology. csupomona. edu/alert/igneous/texture. htm

Pumice • Fun fact- this rock is also called “Lava froth” • Color- Light • Texture-porous and rough, formed at earths surface so it has very few crystals • This rock is not porphyritic, it typically contains only one type of mineral http: //geology. com/rocks/igneous-rocks. shtml

Rhyolite • Fun fact- Rhyolite has a composition of over 60% silicon • Light in color • Fine grained, aphanitic texture, crystals are very small and can hardly be seen by the unaided eye • It is extrusive • Not porhphyritic http: //geology. com/rocks/igneous-rocks. shtml

Obsidian • • • Fun fact: also known as nature’s glass Dark in color Glassy texture Extrusive Non porphyritic http: //geology. com/rocks/igneous-rocks. shtm l

Quartz composite igneous rock • Fun fact- minerals can make up rocks, but rocks can not be minerals • Color- light • Texture- coarse grained • This rock is an intrusive igneous rock http: //geology. com/rocks/igneous-rocks. shtml

Andesite • Fun facts-Andesite is the most common volcanic rock after basalt. • Color-Lighter gray, contains about 50% silicon • Texture-fine grained • Extrusive • This is a porphyritic rock because it contains the minerals quartz, horns blend, and mica http: //geology. com/rocks/igneous-rocks. shtml

Pegmatite • Fun fact- this rock often fools people into thinking it is sedimentary because of its very coarse texture and large crystal deposits • Color- displays a wide variety of color • Very coarsed grained texture • Intrusive • Porphyritic- typically containing a mixture • Of quartz, feldspar, and mica http: //geology. com/rocks/igneous-rocks. shtml

Basalt • One of the most common mafic igneous rocks *It’s on pg. 37 in your textbook • Color darker/ mafic rock • Fine grained texture • Extrusive • It is pyrophyritic http: //geology. com/rocks/igneous-rocks. shtml

Scoria • Fun fact: it is bubbly, it is often used for a base to make roads • Color- dark gray to black • Vesicular texture/ coarse grained • Extrusive rock • Can be porphyritic http: //geology. com/rocks/igneous-rocks. shtml

Syenite • Fun fact- looks like granite • Multicolor- typically a white, black, gray blend • Semi-coarse grained • Intrusive rock • Has a blend of different minerals, which makes it porphyritic http: //geology. com/rocks/igneous-rocks. shtml