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