Geology Midterm

What is a mineral?

a naturally occurring, inorganic, crystalline, solid, with a definite chemical formula

What are all the properties of Minerals?

1. Naturally occurring

2. Inorganic

3. Crystalline

4. Solid

5. Definite chemical formula

What does it mean that a mineral is Naturally Occurring?

• Minerals must be produced and found in nature

What are synthetic minerals?

Minerals created in a lab

What does it mean that a mineral is Inorganic?

• Traditionally they are the products of physics and chemistry alone without the aid of biological agents

• However, there are minerals (biominerals) created by organisms

  • Shells of clams

What does it mean that a mineral is Crystalline?

• All minerals have a regular and repetitive framework resulting from an organized set of atoms

• This framework controls the shape that mineral crystals display

What does it mean that a mineral is Solid?

• It’s solid…

• When frozen, ice can be considered a mineral, but as a liquid it cannot

What does it mean that a mineral is Definite Chemical Formula?

• Each mineral is characterized by a set of elements

• Can be expressed as a chemical formula

What is a Mineraloid?

Are substances that are amorphous (have no ordered atomic structure)

What’s the Difference Between a Rock and a Mineral?

-       A rock can be…

o   An aggregate of one or more minerals

o   Composed of mineraloids

o   Composed of solid organic matter

-       Minerals are the building blocks of rocks

What are Minerals composed of?

Minerals are composed of atoms

What is an atom?

Atoms are the smallest particles of matter that cannot be split into simpler substances by chemical processes

What are atoms composed of?

-       Atoms are composed of a nucleus and an electron cloud

-       The nucleus contains positively charged protons as well as neutrons, which do not have a charge

What is atomic mass?

An element’s atomic mass is the sum of its protons and neutrons

What are isotopes?

Atoms of the same element that have different numbers of neutrons

What are the five common bond types?

o   Covalent

o   Ionic

o   Metallic

o   Hydrogen

o   Van der Waals

What are Mineral’s Optical Properties?

• Luster

  • Metallic

  • Non-Metallic

• Streak

• Double Refraction

What is Luster?

How the light is reflected off of a mineral’s surface

What is Streak?

The color of a mineral when it is powdered

What is Double Refraction?

• Splitting light into two beams

• Double refraction is found in the mineral calcite

  • It’s the tv static effect = seeing double when placed on paper

What are Mineral’s Shape Properties?

• Crystal form (habit)

  • the geometric shape it will naturally take if it is given enough space in its growth

What are Mineral’s Mass-Related Properties?

• Specific Gravity

  • think of it practically as how heavy something feels to you given its size

What are Mineral’s Mechanical Properties?

• Hardness

  • measures a mineral’s resistance to being scratched

• Tenacity

  • describes how easily a mineral can be broken or deformed

What is a cleavage plane?

Cleavage plane

• When a mineral breaks along a plane of weakness, it produces a flat surface

  • Depending on a clean the break is, a minerals cleavage can be described as poor, fair, good, or excellent

What is fracture?

Fracture

• If a mineral breaks with no sign of a cleavage plane

  • it can be conchoidal (shell-like)

What do Geologists use to measure the hardness of a mineral?

Mohs’ Hardness Scale

• it’s a scale from 1 - 10 with 1 being the easiest and 10 being the hardest

  • Fingernail – Penny – Glass – Steel – Diamond

Other properties of minerals with their mineral correspondent

-       Odor – Sulfur smells like rotten eggs

-       Taste – Halite is salty, trona tastes alkaline (baking soda)

-       Magnetism – Magnetite

-       Fizzy reaction to acids – Calcite and dolomite (when scratched)

-       Fluorescence – Fluorite glows under a blacklight

What is Olivine?

A green mineral

What is Biotite?

A black mineral that peels apart

What is Orthoclase?

Is usually pinkish

What is Quartz?

Is super common

What is Halite?

Salt

What is Fluorite?

A fluorescent mineral

What is Hematite?

Iron Ore

What is Magnetite?

Naturally magnetic iron ore

What is Limonite?

A yellowish iron ore

What is Pyrite?

“Fool’s gold”

What is Galena?

A heavy, silvery mineral

• Stinks when HCI is applied

What is Gypsum?

A soft “evaporite” mineral

What is Calcite?

It fizzes with acid and possesses double refraction

What is Dolomite?

It will only fizz with acid if it is powdered first

What are Carbonates?

• Minerals with a chemical formula consisting of the carbonate ion ends with (-CO3) bonded to a metal cation

  • Calcite - it fizzes with acid and possesses double refraction

  • Dolomite - it will only fizz with acid if it is powdered first

What are Native Elements?

• Minerals that are made up of only one element

• Examples:

  • Gold

  • Graphite

  • Diamond

During the Rock Transformation Process what is Weathering?

Mechanical or chemical processes that break a larger rock into smaller pieces or its chemical components

During the Rock Transformation Process what is Metamorphism?

Change that occurs in a rock due to extreme amounts of heat and/or pressure (NOT melting)

What is the difference between Magma and Lava?

Lava is magma that erupts from a volcano

• Magma (inside the earth) and Lava (outside the earth)

What are the two types of Igneous Rocks?

• Intrusive

• Extrusive

What are Intrusive Rocks?

Form from magma cooling inside the earth

What are Extrusive Rocks?

Form from lava cooling on the Earth’s surface

Identifying Igneous Rocks (Texture) - What is Pegmatitic?

crystals are larger than 30 mm in size

Identifying Igneous Rocks (Texture) - What is Phaneritic?

crystals are 1-30 mm in size

Identifying Igneous Rocks (Texture) - What is Aphanitic?

crystals are smaller than 1 mm in size (can’t see any crystals)

Identifying Igneous Rocks (Texture) - What is Porphyritic?

a combination of phaneritic and aphanitic texture (bigger crystals floating in crystals that you can’t see)

Identifying Igneous Rocks (Texture) - What is Glassy?

volcanic material that cools so fast the minerals can’t form (it looks smooth and glassy)

Identifying Igneous Rocks (Texture) - What is Vesicular?

contain many tiny holes resulting from volcanic gases escaping from cooling lava (looks like airy sponge)

Identifying Igneous Rocks (Texture) - What is Pyroclastic?

contains fragments of broken volcanic rock because of explosive volcanism

Identifying Igneous Rocks (Composition) - What is Felsic?

Light colored

Identifying Igneous Rocks (Composition) - What is Mafic?

Dark colored

Identifying Igneous Rocks (Composition) - What is Intermediate?

Mix of both light and dark

What are Dikes and Sills?

Are magmatic intrusions that follow cracks or openings in the rock

• Dike – Vertical cracks in the crust

• Sill – Horizonal cracks in the crust

Igneous Rocks - Granite

• Felsic

• Coarse

is commonly used for buildings, tombstones, monuments, statues, countertops, etc…

Igneous Rocks - Rhyolite

Felsic

Fine

Igneous Rocks - Diorite

Intrusive

Intermediate

Igneous Rocks - Andesite

Intrusive

Intermediate

Fine

Igneous Rocks - Gabbro

Intrusive

Mafic

Igneous Rocks - Basalt

Mafic

Fine

Igneous Rocks - Obsidian

Glassy

Igneous Rocks - Pumice

a lightweight vesicular rock that can float in water, is often used in pedicures

What is Migmatite?

a rock that partially melts

What are Protoliths?

The Original Rock

During the heat and pressure of metamorphism, the original minerals in the rock become unstable and change into more stable minerals

Texture - What does Foliated mean?

have foliations (bands of aligned mineral grains) = have lines / layers

Texture - What does Non-Foliated mean?

no foliations = doesn’t look like it has layers

What are types of Metamorphic rocks?

• Regional – have undergone heat and pressure

• Contact – have undergone just heat

• Dynamic – have undergone just pressure

What are Regional Metamorphic Rocks?

are formed by both heat and pressure and are the most common

What is the order of Regional Metamorphic Rocks?

Shale → Slate → Phyllite → Schist → Gneiss

What is Aureole?

When magma from an igneous pluton bakes surrounding rocks the baked zone is the Aureole

What is Marble?

• metamorphosed limestone

• is a Contact Metamorphic Rock

What is Quartzite?

• metamorphosed quartz sandstone

• is a Contact Metamorphic Rock

What is Pseudotachylite?

is a black, glassy rock found at fault zones, landslides, and impact structures (ex. meteor landing). They are indicative of incredibly high pressure/stresses

What is Serpentinite?

• is green, is California’s state rock

• is a Hydrothermal Metamorphic Rock

What is Soapstone?

• feels soapy, has a lot of talc in it

• is a Hydrothermal Metamorphic Rock

What is Eclogite?

• is a very high Pressure/Temperature metamorphism of basalt/gabbro

• Usually red and green

• High Pressure/Temperature Metamorphic Rock

What is Blueschist?

• is a very high Pressure, low Temperatures rock that forms in subduction zones

• a High Pressure/Temperature Metamorphic Rock

What are the 4 basic layers in the Earth?

o   Inner Core

o   Outer Core

o   Mantle

o   Crust

What is the Lithosphere?

The uppermost layer of the mantle combined with the crust

What is the Crust?

• is the outermost skin of the earth

• 5-70 km thick

What are the two ways the Crust can be divided?

• Oceanic crust

  • o   Oceanic crust underlies the Earth’s oceans and is composed of basalt and gabbro

• Continental crust

  • Continental is composed mainly of granite and diorite, often covered by sedimentary rocks

  • The continental crust is thicker than the oceanic crust, but is less dense

What is the Mantle?

-       is just below the crust and contains 84% of the Earth’s volume and 67% of its mass

What is the Asthenosphere?

Right below the lithosphere is the asthenosphere, which flows in a plastic fashion because of higher temperatures

What is the Core?

• the inner core and outer core can collectively be called the core

• The core is mainly made of iron with small amounts of nickel

• The core is 15% of earths volume but 30% of its mass

What is the difference between the Inner Core and the Outer Core?

• The inner core is solid

• The outer core is liquid

What are Plate Tectonics?

pieces of the Earth’s lithosphere (called plates) move in relation to each other

What are Plates?

The Earth’s lithosphere (crust and uppermost mantle) is divided into Plates

Plates are rigid and deform by breaking to produce earthquakes

What are Passive Margins?

found at the edge of continents where the continent and the surrounding oceanic crust are on the same tectonic plate

What are Active Margins?

where the edge of a continent coincides with a plate boundary, and earthquake and volcanic activity is common

What is a Divergent Boundary?

Is found between two plates that move in opposite directions from each other

What is a Convergent Boundary?

are when two plates collide

What are the three types of Convergent Boundaries?

Continental-continental

Continental-oceanic

Oceanic-oceanic

Continental-Oceanic Convergence

Ocean crust is denser than continental crust, so the oceanic crust is forced down into the mantle

Leads to continental arc volcanoes

Oceanic-Oceanic Convergence

When two oceanic crusts collide, whichever plate is slightly colder and denser will subduct

Leads to island arc volcanoes