Lab Exercise - Igneous Rocks Clarification and Identition (1)-1

Geology Lab 1 Lab Exercise - Igneous Rocks Clarification and Identification Name: Date: Part 1 – Rock Cycle 1. List the source(s) of energy that drive the Rock Cycle Complete the Rock Cycle Diagram below: Kaylee Cruz 10/10/23 sun earth's inner heat weathering uplift transportation heat deposition pressure sedimentary burial igneous intrusion extreme heat eruption / crystallization metamorphic

Geology Lab 2 Part 2 – Igneous Rocks: Processes and Rocks Igneous Rocks form as molten rock cools and crystallizes. Crystallizes - as magma cools, the once mobile ions begin to arrange themselves into orderly patterns forming crystals. As cooling continues, numerous crystals develop until all crystals are joined. A very larg e magma body located kilometers beneath the Earth’s surface takes millions of years to cool. This slow cooling allows ions to migrate freely until they eventually join one of the existing crystals, promoting growth of fewer but larger crystals. Molten roc k at the Earth’s surface, such as a thin lava flow, cools rapidly, causing the ions to lose their mobility. The inability to move quickly results in a solid mass of many small intergrown crystal. Magma is molten rock generated by partial melting of rocks in the Earth's mantle and much in much smaller amounts in the lower crust - beneath the Earth's surface. Once formed, a magma body (mantle plume) buoyantly rises to the earth’s surface because it is less dense than surrounding rocks. Occasionally, molten rock reaches the Earth’s surface where it is called l ava . Igneous rocks that form wh en molten rock solidifies at the Earth’s surface are classified as extrusive rocks, also known as volcanic rocks. When magma crys tallizes beneath the Earth’s surface, "forms at Depth", these igneous rocks are termed intrusive rock, also known as plutonic rocks. Intrusive rocks remain at depth, beneath the Earth's surface unless the portions of the crust are uplifted and the overlying rocks are stripped away by erosion and exposing the intrusive igneous rock. Part 3 – Igneous Rock ’ s Texture The geological definition of a rock’ s Texture is the size, shape and arrangement of mineral grains observed an igneous rock sample. Igneous rock ’ s texture is determined by the rate at which the molten elements cooled. Texture is important because it allows geologist to make inferences the rock's origins. Igneous rocks that form at the Earth’s surface where cooling is relat ively rapid are composed of crystals too small to be s seen with the unaided eye are said to exhibit an aphanitic texture . When large bodies of magma slowly crystallize at great depths, they form igneous rocks composed of crystals that are roughly equal in size and large enough so that the individual mineral crystals can be identified with the unaided eye are said to exhibit a phaneritic texture . Pegmatitic texture is very coarse grained. Magma requires thousand to millions of years to solidify. Different mineral crystallizes under different temperatures and pressure, so some molten rock may contain already formed crystals. Once the remaining molten rock cools, the rock texture characterized by two distinct crystal sizes is called porphyritic . The larger crystals are called phenocrysts and the matrix of the smaller crystals is the groundmass. A glassy texture is unordered ion s “frozen in place” before they were able to unit into an orderly crystal . A result of molten rock ejected into the atmosphere where it cools rapidly and becomes a solid. Vesicular texture – A term applied to many extrusive rocks that are described as fine-grained igneous rock and exhibits voids of many small cavities that represent gas bubbles that formed as lava cooled Part 4 – Igneous Rock ’ s Composition Igneous rocks are composed mainly of oxygen and silicon , expressed as silica (SiO 2 ). These two elements plus Aluminum (Al), Calcium (Ca), Sodium (Na), Potassium (K), Magnesium (Mg) Iron (Fe) – make up 98% by weight of most magmas. As magma cools and solidifies, these elements combine to form two major of silicate minerals dark silicates - rich in iron and/or magnesium and are low in silica. The light silicates contain greater amount of potassium, sodium and calcium and are richer in silicate than darker silicates.

Geology Lab 4 Part 6 – Igneous Rock Analysis and Classification Geologist classify igneous rocks on the bases of their texture and composition.

Geology Lab 5 6. Identify the igneous textures visible in Images A, B, C, D, E and F in the figure above. A B C D E F 7. Then use the textural information to infer the rock ’ s origin (how the rock formed). A B C D E F A B C D E F resicular porphyritic pyroclastic/fragmental aphanatic ↑ haneritic glassy formed from gas bubbles that burst magma sat and cooled a bit below the Earth's in the lava as it was cooling surface , giving time for the large crystals t o form derived from magma or plucked as formed when the material solidifies at or solid pieces from the walls of the conduit near the surface so that the cooling is rapidl forms when magma deep underground occurs during some volcanic eruptions when -F in the plutonic environment cools down I4n'n" ched so rapidly that crystalliza-

Geology Lab 7 Using the figure above, answer the following questions: 9. Igneous rocks with crystals so small they can only be viewed by microscopes are said to exhibit a texture termed . 10. Rocks that contain crystals that are roughly equal in size and can be identified with the unaided eye are said to exhibit a texture termed . 11. A texture is a result of unordered ions are “frozen in place” before they were able to unit into an orderly crystal. 12. texture - An igneous rock texture resulting from the consolidation individual rock fragment occurring during a volcanic eruption. 13. Which igneous texture would be the most common found in a volcanic lava flow? 14. Which igneous texture would be the most common found in a pluton? Part 7 – Igneous Rock Identification Using Hand Samples 15. Obtain a set of igneous rocks as directed by your instructor. The fill in the formation on the following Igneous Rocks Hand Sample Worksheet. fine grained Aphanitic coarse grained Phaneritic glassy pyroclastic texture aphanitic Phaneritic

N ame: Date: Rock Sample (Place rock in square) Texture(s) Present Mineral Present and Their % Abundance Color Index Andesite (Place rock in square) Basalt (Place rock in square) Diorite (Place rock in square) Igneous Rock Identification Stamp: How did the rock form page 1 Kaylee Cruz 10/10/23 granite typically found in 2 dark volcanos avove fine gray convergent plate grained Dasalt Doundaries 16 + 45 % fine . Igneous , forms as an extrusive grained plagiociase ed rock such as lava but can also form in small intrusive bodies 46+085 % course plagioclast , black usually occurs as / grained pyroclastic 2 large intrusions & Igneous white sills within the rock continental crust 16 to 45 %

Pumice (Place rock in square) Rhyolite (Place rock in square) Scoria (Place rock in square) Volcanic Tuff (Place rock in square) page 3 mineraloid light forms during explosive I extremely colored VOKanI porous , lightweight eruptions , gas concrete bubbles are trapped - & to 25 % I Inrock during rapid cooling very nigh grautz , pink or forms from granitic - - Silica plagioclase , gray magma partially cooled S content sandine In the subsurface S grains small & +O 15 % abundants iron & . blacks forms when W round , magnesium dark magma containing grey , bubble deep abrudant dissolved like redish gas flows Is blown cavities 45 to 85 % brown out during a volcano lens feldspar black , forms from shaped and quartz dark and small ↑ roducts of an thick amount of green , & Oh explosive eruption calcedony red 0 - 85 %

Vesicular Basalt (Place rock in square) Pegmatitic Granite (Place rock in square) Porphyritic Andesite (Place rock in square) page 4 coarse zeolite , gray formed as , gas - I grained pumpellyite bubbles In lava filled w/ secondary - minerals 451085 % large topaz , light form ed during the crystals colored ↑ beryl final stage of magmas crystalization 0 - 15 % visible ground mass generally of Greyish formed through e rystals , Pyroxene and to fine plagioclase purple Slow and fast 3 - / grained . MN cooling 1870 45 %