Geology 1010 Lab Exam Studying

Sandstone (Sedimentary)

Sandstone (Sedimentary)

Detrital, well sorted, does not react with acid, harder than glass

Conglomerate (Sedimentary)

Detrital, rounded pebble clasts, relatively similar sized grains

Limestone (Sedimentary)

Chemical, contains fossils, Ooids has small rounded grains while fossiliferous is very fine grained with large fossil fragments- reacts with acid

Coquina (Sedimentary)

Chemical, composed of shell fragments, reacts with acid, looks "layered," can be "orangish color"

Coal (Sedimentary)

Organic, black, lustrous, friable

Chert (Sedimentary)

Chemical, smooth, blocky, harder than glass, layered.

Shale (Sedimentary)

Detrital, dark rock with parallel breakage surfaces. Friable, no large grains.

Schist (Metamorphic)

Foliated: schistosity, coarse grained combination of light and dark minerals, satin-like sheen, softer than glass

Slate (Metamorphic)

Foliated: slaty cleavage, dark grey color, very fine gained, dull luster, harder than glass

Gneiss (Metamorphic)

Foliated: gneissic banding, striped pattern of light and dark minerals, coarse grained, harder than glass

Marble (Metamorphic)

Non-foliated, generally light colored, very coarse grained crystals, reacts with acid, glassy luster, softer than glass

Quartzite (Metamorphic)

Non-foliated, light color translucent crystal grains, does not react with acid, glassy lister, harder than glass

Phyllite (Metamorphic)

Foliated: Phyllitic, very fine crystals, pale grey color, does not react with acid, satin-like sheen, softer than glass

Quartz (Mineral)

Hardness: >5.5, fractured, any color, vitreous, colorless streak

Muscovite (Mineral)

Hardness: <5.5, perfect cleavage in one direction, colorless in thin sheets with hints of yellow, green, brown, or rose. Vitreous or pearly luster, white streak.

Calcium Plagioclase (Mineral)

Hardness: >5.5, perfect cleavage in two directions, color: clear, white, gray, vitreous to pearly on cleavage faces, white streak. Has labradorescence, an optical interference of light which appears multicolor.

Galena (Mineral)

Hardness: <5.5, perfect cleavage in 3 directions meeting at 90 degrees, silver to gray color, metallic luster, lead gray to black luster.

Magnetite (Mineral)

Hardness: 5 to 6.5, no cleavage, black to silvery gray color, metallic to submetallic luster

Pyrite (Mineral)

Hardness: >5.5, fracture, brassy yellow color, metallic luster, dark greenish/brownish streak

Calcite (Mineral)

Hardness: <5.5, perfect cleavage in three directions, any color, glassy, white streak, fizzes in the presence of a strong acid

Graphite (Mineral)

Hardness <5.5, perfect cleavage in one direction, steel gray to black color, metallic to submetallic color

Talc (Mineral)

Hardness <5.5, perfect cleavage in one direction, green, white, pink or gray color. Luster: nonmetallic, streak: white

Halite (Mineral)

Hardness: <5.5, perfect cleavage in three directions meeting at 90 degrees. White, colorless, yellow, gray, black, red, brown color, vitreous luster, white streak

Pyroxene (Mineral)

Hardness: 5 to 7, two directions of cleavage, dark green, black, or dark brown color, vitreous luster, white streak

Amphibole (Mineral)

Hardness: 5 to 6, cleavage in two directions, black, dark green, dark brown. Vitreous luster, white or colorless streak.

Potassium Feldspar (Mineral)

Hardness: >5.5, cleavage in two directions. Pink, white, gray, or green color, nonmetallic luster, white streak.

Olivine (Mineral)

Hardness: >5.5, fracture, vitreous color, colorless streak. Green, yellowish green, brownish red, or brown color.

Sodium Plagioclase (Mineral)

Hardness: >5.5, perfect clevage in one direction and very good cleavage in one direction, pearly/vitreous luster, white streak. Color: white, green, or gray.

Gypsum (Mineral)

Hardness: <5.5, perfect cleavage in one direction, poor cleavage in two directions, vitreous luster, white streak. Color: clear, colorless, white, brown, gray, yellow, red.

Fluorite (Mineral)

Hardness: <5.5, perfect cleavage in four directions, vitreous luster, white streak. Black, red, blue, colorless, yellow, purple, green.

Sulfur (Mineral)

Hardness: <5.5, no cleavage, greasy luster, yellow streak. Color: yellow, brownish yellow, greenish yellow.

Kaolinite (Mineral)

Hardness: <5.5, perfect cleavage in one direction, pearly to dull earthy luster, white streak. Color: white (occasionally with red, blue, yellow, or brown tints.

Hematite (Mineral)

Hardness: 5 to 6.5, no cleavage, earthy luster, red to reddish brown streak, color: red to reddish brown.

Biotite (Mineral)

Hardness: <5.5, perfect cleavage in one direction, vitreous luster, white/gray streak. Color: black, dark brown, dark green

Pumice (Igneous)

Vesicular texture, felsic composition, extrusive formation. Light color, very fine rained, various sized vesicles.

Volcanic Breccia (Igneous)

Pyroclastic/fragmental texture, felsic/intermediate OR mafic/intermediate composition, extrusive formation. Angular rock fragments >2mm, some vesicles, fine grained particle, usually pink or grayish color.

Granite (Igneous)

Phaneritic/crystalline texture, felsic composition, intrusive formation. Coarse grained, mostly light minerals with some dark, colors vary.

Obsidian (Igneous)

Glassy texture, felsic composition, extrusive formation. Smooth glassy texture, fracture, dark red/black color.

Basalt (igneous rock)

Aphanitic/crystalline texture, mafic composition, extrusive formation. Very fine grained, dark color.

Diorite (Igneous)

Phaneritic/crystalline texture, intermediate composition, intrusive formation. Relatively equal amounts of light and dark minerals, coarse mineral sizes. (diorite = dalmation)

Scoria (Igneous)

Vesicular texture, mafic composition, extrusive formation. Dark color, very fine grained, various sized vesicles.

Gabbro (Igneous)

Phaneritic/crystalline texture, mafic composition, intrusive formation. Medium grains of mostly dark and some light materials.

What minerals have special properties?

Magnetite (magnetic), Calcium plagioclase aka labradorite (has labradorescence), Calcite (fizzes in the presence of an acid)

How are igneous rocks formed?

When hot, molten rock crystallizes and solidifies.

Intrusive vs Extrusive formation

Extrusive rocks are solidified lava which flowed over the earth’s surface, while intrusive rocks are made of magma which solidified underground. Intrusive formation has a slower cooling rate size, resulting in larger crystal sizes, while extrusive has a quicker cooling rate which results in smaller crystal sizes.

What is the difference between felsic, intermediate, and mafic?

Felsic rocks are lighter colored and have higher silica percentages, intermediate has more iron and magnesium content and is medium colored, while mafic is dark colored and has the most magnesium and iron content and the least silica.

How are sedimentary rocks formed?

Existing rock fragments buried under sediment, becoming compacted and cemented.

How are metamorphic rocks formed?

When rocks are subjected to high heat, high pressure, hot fluids, or a combination.

Slaty Cleavage

Parallel foliations of fine grained/platey minerals. Cleavage made from thin slates of rock. Very fine-grained micas.​​

Phyllitic Texture

Flakes very small, barely visible to the naked eye. ​
Fine-grained micas. ​​

Schistosity

Parallel foliations of fine grained/platy minerals. Mica and chlorite crystals begin to grow. Larger micas (shiny).​​

Gneissic Banding

Minerals arranged in bands that look like layers

How does foliation occur?

When pressure is high enough in one orientation so as to flatten the parent rock material or to induce the platy minerals to crystallize in an orientation perpendicular to the direction of the highest pressure

Prolith of schist

Shale

Prolith of slate

Shale

Prolith of marble

Limestone

Prolith of quartzite

Sandstone

Prolith of phyllite

Shale

Primary mineral of sandstone

Quartz

Primary mineral of limestone, conglomerate, and coquina

Calcite