GEOL 1010 - Lab Midterm

What is the difference between a rock and a mineral?

Minerals have an orderly structure and characteristic chemical composition. Rocks are a mix of two or more minerals.

For minerals, what does the Mohs scale mean?

Hardness

What is a streak?

The color of a mineral’s powder when it is rubbed against a textile plate.

A mineral that breaks cleanly along smooth plane lines has

Cleavage

Which of these is NOT a mineral property?

Shape

Which of the following is NOT a mineral?

Calcite, Sandstone, Hematite, Halite

Sandstone

What is luster?

The way a mineral reflects light

Which mineral could you scratch with your fingernail (aka, which a hardness or <2)?

Talc

What property is the LEAST helpful for identifying a mineral?

Color

When a mineral has cleavage, what causes breakage to occur in a certain way?

The relative weakness of some atomic bonds compared to other, stronger bonds in the mineral’s crystalline structure.

Which of the following is NOT a component texture?

Color

Materials with low viscosity

Flow easily

Minerals that are cooled at slow rate usually have

Larger crystals

Light-colored minerals (typically made of silica) are referred to as?

Felsic

Which of these options is NOT one of the main components of magma?

Melt (liquids), Felsics, Solids, Volatiles (gases)

Felsics

Sedimentary rocks form when sediments are:

Compressed and Cemented

Which of the following is a category of sedimentary rocks?

Phaneritic, Sandstone, Chemical, Mud

Chemical

Which of the following is an example of an organic sedimentary rock?

Shale, Coal, Chert, Conglomerate

Coal

Clastic rocks are classified by:

Grain shape, Grain size, Sorting

Fossils are most commonly found in:

Sedimentary rocks

Processes that produce metamorphic rocks include:

Elevated levels of temperature, changes in pressure, chemically active fluids

When individual mineral grains become parallel to one and other due to increased pressure, it is known as:

Foliation

Which of the following is NOT a metamorphic rock?

Shale, Schist, Slate, Marble

Shale

During metamorphosis, minerals in the rock are often altered/changed. Why does this change occur?

Minerals change in order to become more stable at new conditions

Metamorphic rocks:

Form when existing rocks are transformed

• Dark Grey

• Metallic

• 3 planes of cleavage at 90 degrees

• Hardness: 2.5

Galena

• Black

• Submetallic

• Magnetic

• Hardness: 5.5-6

Magnetite

• Grey

• Metallic

• Hardness: 5.5-6.5

Hematite (specular)

• Gold

• Metallic

• Hardness: 6-6.5

Pyrite

• Black

• Metallic

• Cleavage in 1 direction

• Makes marks are paper

• Hardness: 1-2

Graphite

• white/pearly

• Chalky

• 1 plane of cleavage

• Hardness: 1

Talc

• Clear

• Glassy

• Hardness: 7

Quartz

• Greenish black (more green than amphibole)

• 2 planes of cleavage at 87 and 93 degrees

• Hardness 5-6

Pyroxene

• Black

• metallic

• 2 planes of cleavage at 124 and 54 degrees

• Hardness: 5-6

Amphibole

• Pinkish orange

• Non-metallic

• Hardness: 6

Potassium Feldspar

• clear and brown

• 1 plane of cleavage

• Breaks apart in sheets

• Hardness 2.5-3

Muscovite

• Black

• Non-metallic

• Hardness: 2.5-3

Biotite

• Green with small black specks

• Non-metallic

• Hardness: 6-6.5

Olivine

• Light pink

• Glassy

• Hardness: 7

Rose Quartz

• Grey/black

• Labradorescence

• Perfect cleavage in 2 directions intersecting at 86 degrees

• Hardness: 6-6.5

Calcium Plagioclase (Labradorite)

• White/grey/brown

• Perfect cleavage in 1 direction, good cleavage at 90 degrees

• Hardness: 6-6.5

Sodium Plagioclase

• Reddish brown

• Solidified rust

• Hardness: 5.5-6.5

Hematite

• Clear

• Type of salt

• Perfect cleavage in 3 directions

• Hardness: 2.5

Halite

• clear/white

• pearly 3 planes of cleavage

• Hardness: 1.5-2

Gypsum

• White/off-white

• 3 planes of cleavage

• Reacts to acid

• Hardness: 3

Calcite

• Purple, blue, white, clear

• 4 planes of cleavage

• Hardness: 4

Fluorite

• Yellow

• Hardness: 1.5-2.5

Sulfur

• Tan

• Hardness: 6.5-7

Garnet

• White

• 1 plane of cleavage

• Hardness: 2-2.5

Kaolinite

• Brown/black

• Submetallic

• 6 planes of cleavage

• Hardness: 3.5-4

Sphalerite

• Tan

• Detrital

• Fine grains

• Well sorted

Sandstone Quartz Arenite

• Grey/tan

• Detrital

• Coarse grains

• Poorly sorted, big pebbles mixed with other grain sizes

Breccia

• Brown/red

• Detrital

• Mix of fine and medium sized grains

Sandstone Arkose

• Light brown

• Detrital

• very fine grains, silt/clay

• Breaks very easily

Mudstone

• Black

• Organic

• Lustrous

• Lightweight

Coal

• Fossils

• Chemical

• Reacts with acid

• Mix of grain size

Limestone Fossiliferous

• Tan

• Chemical

• reacts with acid

• Tiny holes

Limestone Ooids

• Made of fossils (shells)

• Chemical

• Reacts with acid

Coquina

• Tan and grey

• Chemical

• Smooth

Chert

• Variety of grain sizes

• Detrital

• Reacts with acid

Conglomerate

• Grey/Black

• Detrital

• Smooth

• Fine grains, slit/clay

Shale

• Grey/black

• Foliated, slaty cleavage

• low metamorphic grade

• fine grained

• dull

Slate

• Slivery

• Fine crystals

• Foliated phyllitic (flakes)

• Medium metamorphic grade

Phyllite

• Light and dark minerals

• Coarse-grained

• Foliated, schistosity

• Medium metamorphic grade

Schist

• Striped with light and dark minerals

• Coarse grained

• Foliated, gneissic banding

• High metamorphic grade

Gneiss

• Tan/orange

• Medium sized crystal grains

Quartzite

• Pink/orange

• reacts with acid

• Large crystal grains

Marble

• black

• small glitter crystals

• Coarse grain size

• Foliated, schistosity

Amphibolite

Metamorphic grades of Shale

Prolith → Low grade → medium grade → medium grade → high grade

Shale → Slate → Phyllite → Schist → Gneiss

• phaneritic/crystalline

• Mafic, dark in color

• Intrusive

• Medium grains

Gabbro

• Phaneritic/crystalline

• intermediate

• intrusive

• dark and light minerals

• salt and pepper appearance

Diorite

• Phaneritic/crystalline

• Felsic

• Intrusive

• Red and black grains

• very coarse

Granite

• Aphaneritic/crystalline

• Mafic, dark in color

• Extrusive

• Fine grains

Basalt

• Glassy

• Felsic (still dark in color)

• Extrusive

• Smooth

Obsidian

• Aphanitic/crystalline

• Felsic, light grey

• Extrusive

• Fine-grained

Rhyolite

• Tan with darker fragments

• Fragmental/pyroclastic

• Felsic/intermediate

• Extrusive

• Random pieces of other rocks

Volcanic Breccia

• Vesicular

• Mafic, dark brown or red

• Extrusive

• Fine grained

• lightweight

Scoria

• Vesicular

• Felsic, light grey

• Extrusive

• Fine grained

Pumice

• Pyroclastic

• Felsic/intermediate

• Extrusive

• Fine grained

• Vesicular

Tuff

• Porphyritic

• Intermediate/mafic

• Extrusive

• Large dark minerals in fine grains

Andesite