Unit 3: Earth Materials Classify common minerals according to their physical and chemical characteristics - define mineral chemistry terms. Include: (i) Atom (ii) Ion (iii) Element (iii) Compound (iv)Molecule Describe how atoms combine to form compounds. Include: (i) Ionic compounds (ii) Molecular compounds (iii) Metallic compounds Outline the abundance of the elements that comprise Earth’s crust. Include: (i) Oxygen (ii) Silicon (iii) Aluminum (iv)Iron (v) Calcium (vi)Sodium (vii) Potassium (viii) Magnesium Define a mineral - recognize the relationship between the abundance of the elements that comprise Earth’s crust and the mineral groups. Include: (i) Silicates (ii) Carbonates (iii) Halides (iv) Sulfides (v) Sulfates (vi) Oxides (vii) Native elements Name and differentiate between the major mineral groups listed above. - identify mineral groups based on mineral formulas Describe the arrangement of silicon and oxygen within a tetrahedron Use instruments effectively and accurately for collecting data

Identify and explain sources of error and uncertainty in measurement and express results in a form that acknowledges the degree of uncertainty Describe the mineral properties that are used for identifying minerals. Include: (i) Crystal shape (form) (ii) cleavage (iii) Fracture (iv) hardness (v) Specific gravity (vi) colour (vii) Streak (viii) lustre (ix) Acid test (x) taste (xi) Magnetism (xii) double refraction (xiii) Fluorescence Explain why minerals exhibit different mineral properties. Include: (i) Type of bonding involved (ii) Elemental composition (iii) Internal atomic structure Identify minerals based on their mineral properties Identify careers that relate to mineral chemistry. Include: (i) Mineralogist (ii) Crystallographer (iii) Geochemist (iv)Gemologist Classify rocks according to their structure, chemical composition, and method of formation - define rock - distinguish between rocks and minerals - recognize that minerals are the building blocks of rocks Analyse the rock cycle as a natural system and explain its structure and dynamics - describe the pathways comprising the rock cycle Recognize that igneous rocks are classified according to their mineral composition and texture Describe how mafic igneous rocks differ from felsic igneous rocks based on chemical composition Identify igneous rocks that have similar chemical compositions. Include: (i) Rhyolite and granite (ii) Andesite and diorite (iii) Basalt and gabbro

Identify igneous rocks based on texture. Include: (i) Rhyolite and granite (ii) Andesite and diorite (iii) Basalt and gabbro Describe igneous rock textures. Include: (i) Coarse-grained (phaneritic) (ii) Fine-grained (aphanitic) (iii) Glassy (compact and frothy) (iv)Vesicular (v) Porphyritic Describe how cooling rate and mineral composition determine rock types based on Bowen’s reaction series Identify igneous rocks based on mineral composition and texture Relate personal activities and various scientific and technological endeavours to specific science disciplines and interdisciplinary studies Analyse and describe examples where scientific understanding was enhanced or revised as a result of the invention of a technology Describe the functioning of domestic and industrial technologies, using scientific principles Analyse society’s influence on scientific and technological endeavours Debate the merits of funding specific scientific or technological endeavours and not others Describe the formation of kimberlite and its relationship with diamond deposits Describe the origin and process of formation of sedimentary rocks Describe the classes of sedimentary rocks. Include: (i) clastic (detrital) (ii) chemical (iii) biochemical Identify clastic sedimentary rocks. Include: (i) shale (ii) siltstone (iii) sandstone (iv) conglomerate (v) breccia

Relate sediment sorting to clastic sedimentary rocks Relate particle size to current Velocity Describe the environments and rock types that relate to clastic sedimentary rocks. Include: (i) fluvial (rivers, streams) (ii) lagoonal (iii) beaches (iv) deep marine/ocean (v) shallow marine Identify chemical sedimentary rocks. Include: Evaporites (i) Halite (ii) Gypsum (iii) Sylvite Precipitates (i) Limestone (ii) Dolomite (iii) Travertine Describe the environments and rock types that relate to chemical sedimentary rocks. Include: (i) shallow marine (ii) deep marine/ocean (iii) cave Identify biochemical sedimentary rocks. Include: (i) coquina (ii) chaulk (iii) chert (iv) limestone (coral) (v) coal Describe the sequence of formation of coal. Include: (i) peat (ii) lignite (iii) bituminous (iv) anthracite Describe the environments and rock types that relate to biochemical sedimentary rocks. Include: (i) swamp (ii) shallow marine (iii) beach (iv) deep marine

Identify sedimentary rocks Identify limitations of a given classification system and identify alternative ways of classifying to accommodate anomalies Identify and apply criteria, including the presence of bias, for evaluating evidence and sources of information Communicate questions, ideas, and intentions, and receive, interpret, understand, support, and respond to the ideas of others Evaluate individual and group processes used in planning, problem solving and decision making, and completing a task Describe the process of metamorphism Describe possible changes that result from metamorphism. Include: (i) texture (ii) volume change (iii) chemical change Describe the result of selected rocks being metamorphosed. Include: (i) limestone to marble (ii) sandstone to quartzite (iii) shale to slate (to phyllite to schist to gneiss) (iv) granite to gneiss Contrast the two types of metamorphism. Include: (i) contact (ii) regional Describe the locations where contact metamorphism occurs. Include: (i) beneath lava fl ows (ii) adjacent to magma intrusions (iii) dykes and sills Describe how contact metamorphism can be used to distinguish between a buried lava flow and an intrusion of magma. Describe the locations where regional metamorphism occurs. Include: (i) areas of mountain building (ii) subduction zones

Identify metamorphic rocks Identify careers that relate to the study of rocks. Include: (i) petrology (ii) volcanology (iii) geochemistry (iv) sedimentologist (v) hydrology

NOTES: The chemistry behind minerals In order to better understand minerals we should first understand the chemicals that make them. 1. Atoms The smallest particles that has all the characteristics of an element. It contains a nucleus, which contains protons and neutrons. Outside the nucleus in energy levels, but still within the atom are negatively charged particles called electrons. They are the smallest unit of matter.

2. Ions: Atoms which have become electrically charged due to a gain or loss of electrons. There are 2 kinds: Cation: an atom which has become positively (+) charged; it has lost one or more electrons

Anion: an atom which has become negatively (-) charged; it has gained one or more electrons 3. Elements: Material made of only one type of atom. There are over 100 known elements- 8 make up over 98.5 % of earth’s crust.

4. Compounds: A molecule that contains two or more different types of atoms or ions. A compound can have properties that are entirely different than the elements that make them.

Ex: Halite: is commonly called rock salt. Made of Na and cl. Salt can be eaten but Na and Cl are poisonous by themselves.

5. Molecules: Are combinations of two or more atoms.( Molecular element - if the atoms are all the same.) When an atom combines (bonds) with another atom to form a molecule, one of 3 things will happen: It will lose electrons (become positively charged)

It will gain electrons (become negatively charged)

It will share electrons

In an ionic bond, electrons are transferred from one atom to another; one atom loses electrons (becomes a positively charged cation ) and one atom gains electrons (becomes a negatively charged anion). In a covalent bond, electrons are shared between atoms. This bonding pattern is responsible for the atomic arrangement and physical structure of halite (salt), Atomic Arrangement in Halite (Salt) Physical Structure of Halite (Salt)

Covalent bond: Example: Methane gas (CH4). Electrons are shared between atoms in the molecule. NOTE: Covalent bonding is responsible for the atomic arrangement and physical structure of graphite. Graphite is composed of carbon atoms which are covalently bonded in hexagonal rings. A dominantly layered structure of strongly bonded carbon atoms are held together by weaker bonds between the layers. This weak bonding between the layers attributes to graphite’s low value of hardness and its cleavage pattern.

Elements found in the earths crust.

1. Oxygen(46.6%) 2. Silicon (27.7%) 3. Aluminum-(8.1%) 4. Iron(5%) 5. Calcium (3.6%) 6. Sodium(2.8%) 7. Potassium(2.6%) 8. Magnesium (2.1%)

A mineral: Is a naturally occurring solid with a definite chemical composition and molecular

structure. Minerals can consist of elements or compounds. Majority are compounds. Native minerals consist of only one type of element. Examples include gold silver

diamond and copper. To be a mineral you must satisfy the following:

Occur in nature Inorganic Solid Definite chemical composition Definite molecular structure

Rock: A rock is a consolidated mixture of one or more minerals. Ex: Granite consist of more than one mineral. Quartz, Feldspar, Hornblende, and mica. Some common rocks include;

Igneous: Granite, Rhyolite, Basalt, Gabbro, obsidian, Pumice, etc.. Sedimentary: Conglomerate, Sandstone, Shale, Limestone, etc... Metamorphic: Marble, Slate, Gneiss, Schist, Phyllite, etc...

Rock forming minerals: The rock cycle suggest that ALL rock types started as igneous rocks. (Solidified magma) Igneous rocks form from eight minerals called Rock forming minerals:

1. Olivine 2. Pyroxine 3. Amphibole

4. Biotite Mica 5. Plagioclase Feldspar 6. Orthoclase Feldspar 7. Muscovite Mica 8. Quartz

Mineral groups: Elements that comprise Earth’s crust and the mineral groups. Include: (i) Silicates (ii) Carbonates (iii) Halides (iv)Sulfides (v) Sulfates (vi)Oxides (vii) Native elements

1. Silicates: a mineral group that has silicon and oxygen as part of their atomic structure. Comprise more than 96% of the earth’s crust. The silicon-oxygen tetrahedron

is the structure that is common to all minerals in the silicate group.

Two groups: 1. Sialic silicates(Aluminosilicates) Rich in silicon and aluminum. Main rock type found in continents and comprise about 85% of the crust. Minerals are light in colour. 2. Simatic silicates

Rich in silicon and magnesium Main rock type found in the ocean floor and comprise less than 15% of the crust. Minerals are dark in color.

Silicate Structures

Silicates are the most common type of mineral group in Earth’s crust. Perhaps one of the reasons why there are so many minerals in this group is because of the number of different ways the silicon oxygen tetrahedron (the basic structure of all silicate minerals) can bond to each other.

This is the silicon-oxygen tetrahedron, the basic unit of the silicate group of minerals. Here the oxygen:silicon ratio is 4:1. This is the mineral olivine (Mg, Fe)2SiO4, one of the simplest silicates. Here, the individual tetrahedra are not bonded together. The structures in this picture are chain silicates. In the single chain silicates, tetrahedra are bonded to each other. In the double chain silicates, these single chains are bonded together.

This is the structure found in sheet silicates, including micas. Here, several chains of tetrahedra are bonded together. 2. Carbonates: compound consisting of an atomic structure of one carbon and three oxygen. (CO3) Most common carbonate is calcite which makes up the rock limestone. (CaCO3)

3. Halides: compounds consisting of an atomic structure of chlorine or fluorine with

sodium, potassium or calcium.

Halite (NaCl) is the most common halide. Often referred to as table salt.

4. Sulphides: Compounds consisting of an atomic structure of one or more metals

combined with sulphur.

Common ore mineral. Examples: Pyrite (FeS2), Galena (PbS), Sphalerite (ZnS)

5. Sulfates: compounds consisting of an atomic structure of one sulphur and four oxygen.

(SO4)

Gypsum is an example of a sulphate and it also takes on its mineral name. (CaSO4 2 H2O)

6. Oxides: Compounds consisting of an atomic structure of oxygen combined with one or

more metals. The most common oxides are those of iron (Fe2O3), Aluminum (Al2O3),

referred to as ore-minerals.

7. Native Minerals:

o Elements that occur in an un-combined state in nature.

o Commonly called native elements

o Examples: Gold(Au), Silver (Ag), Copper (Cu), & Sulfur(S)

Hints to classify mineral groups.

Mineral groups that end in “ide” and have a metal ( eg:Na, K) in its chemical formula are one of

the following:

Oxides: Metal + O

Sulfides: Metal + S

Halides: Metal + Cl,Br, F

Mineral groups that end with “ate” and have an oxygen group in its chemical formula are one

of the following:

Silicates: Si +O

Sulphate’s: S + O

Carbonates: C +O

Mineral Properties:

Each and every mineral has certain mineral properties. The properties of each mineral depend on the

following.

1. The type of elements present

2. The arrangement of the atoms

3. The strength of bonding

The following are a list of physical properties that each mineral displays.

1. Specific gravity

2. Hardness

3. Cleavage

4. Streak

5. Lustre

6. Color

7. Others (taste, feel, magnetism, acidity and fluorescence)

Specific gravity: Is the mass of a mineral compared to that of an equal amount of water.

Since 1g=1cm3=1ml, this can be done very simply.....

To determine the specific gravity you need to carry out the following three steps:

1. Weigh the specimen in air and record the weight.

2. Weigh the specimen submerged in water (equal to the amount of water displaced) and

record the weight.

3. Calculate the specific gravity using the following formula.

Example:

A mineral sample with a mass of 75 g is placed in a graduated cylinder with 100 ml of water. The water level rises to 125 ml in the cylinder. What is the specific gravity of the mineral?

Ans: Since the mineral displaces 25mls of water and 25mls=25g, we simply divide…

Hardness is a measure of how difficult it is to scratch a mineral. Friedrich Mohs tested many

minerals and developed a scale of 10 minerals that he ranked with a hardness value of 1 to 10.

The higher the number on the Mohs Hardness Scale, the harder the mineral.

Mineral Mineral Hardness Hardness of Common Objects

Talc 1 softest Soft pencil point (1.5)

Gypsum 2 Fingernail (2.5)

Calcite 3 Copper penny (3.5)

Fluorite 4 Iron nail (4.5)

Apatite 5 Glass (5.5)

Feldspar 6 Steel file (6.5)

Quartz 7 Streak plate (7)

Topaz 8 Sandpaper (7.5)

Corundum 9 Emery paper (9.0)

Diamond 10 hardest

Cleavage

You can get important clues to a mineral’s identity by breaking it apart. Sometimes a mineral

has cleavage, which means it splits along smooth, flat surfaces called planes. Mica is an

example of a mineral with cleavage. Separating the layers of mica is a bit like separating the

pages in a book. Not all minerals have cleavage. The Cleavage directions are determined by

atomic structure and strength of bonding. Cleavage follows areas of weak bonding. Minerals

show cleavage in many different directions but most common are in planes of one, two and

three directions. Cleavage in one direction ( basal cleavage) occurs in mica.

Fracture Minerals may have fracture, which means they break with rough or jagged edges. Quartz is an

example of a mineral that fractures when it is broken apart. In order to examine cleavage and

fracture, you need to look at a freshly broken surface of a mineral.

Streak A way to identify a mineral is to rub it across a piece of unglazed porcelain tile (Figure 10.2). The

mark it makes is called a streak, which is the powdered form of the mineral and the True color.

Lustre One clue to the identity of a mineral is how shiny it is. The shininess, or lustre, of a mineral

depends on how light is reflected from its surface. If a mineral shines like a polished metal

surface, it has a metallic lustre. If a mineral reflects light like a piece of glass, it has a glassy

lustre. If the mineral does not reflect light well, it has a dull lustre. A pearly lustre is one where

it looks as if it has a layer of pearl. Ex: Talc.

Color Color may seem like an easy way to identify minerals, but color alone is not reliable. One type

of mineral may have different colors and different minerals can have the same colors.

Also, some minerals can have impurities which cause a single mineral to have different colors

All of these gems are formed from corundum. Corundum is white

when it is pure, but when it

Contains iron it is blue. When corundum contains chromium, it is red

Other Properties of Minerals

Acid test: An acid test would involve dropping acid on a sample to see if the mineral reacts

(fizzes) this is used to test the carbonate group.

Taste: is not the first (or possibly even the last) property someone would associate with minerals. And yet, taste is sometimes a very good characteristic and a key to identification in some cases. The most commonly "tasted" mineral is halite or rock salt, but there are several other minerals that have a distinctive taste.

When tasting a mineral, do not lick the specimen. It is recommended that the testing person first wet their finger, then place the wet finger on the specimen and finally taste the finger.

Magnetism: The Magnetic Minerals are few, but the property is important because of this fact. Once a specimen is established as magnetic, identification becomes a rather routine exercise. The mineral magnetite is named after this characteristic.

Double refraction: Double refraction occurs when a ray of light enters a crystal and the ray is split into beams, one very fast and one very slow; relatively that is. As these two beams exit the crystal, they are bent into two different angles (the angles of refraction) because the angle is directly affected by the speed of the beams. A person viewing into the crystal will see two images ..... of everything. The best way to view the double refraction is by placing the crystal on a straight line or printed word (the result will be two lines or two words). Fluorescence: The light from these ultraviolet lamps reacts with the chemicals of a mineral and causes the mineral to glow; this is called fluorescence. If the mineral continues to glow after the light has been removed, this is called phosphorescence. Some minerals will glow when heated; this is called thermo luminescence. And there are some minerals that will glow when they are struck or crushed; this is called triboluminescence.

Some other properties of minerals include heft (how heavy it feels), odour, and whether the

surface feels powdery, soapy, or greasy.

Diamond vs. graphite:

Minerals exhibit different mineral properties. Include: (i) Type of bonding involved (ii) Elemental composition (iii) Internal atomic structure Some minerals can have the same chemical compositions but have different physical

properties, ex: hardness and cleavage of diamond and graphite.

Diamond and graphite are forms of pure carbon however, the physical properties, hardness

and cleavage are quite different for the two minerals. This is due to:

1. Different atomic structure of carbon atoms.

2. Strength of bonding between carbon atoms differs for the two minerals.

Diamonds consist of a tetrahedral network of carbon atoms. Most stable atomic structure. The

strength of bonding results in no weak areas. This allows diamond to be the hardest mineral

with no apparent cleavage planes.

Graphite is arranged in sheets or layers. The strength of bonding between layers is weak. Thus

it experiences basal cleavage.

Quartz and mica can also be compared and contrasted. They compare in that both are comprised of the silicon-oxygen tetrahedron. They contrast in that quartz exhibits fracture and mica exhibits basal cleavage. Careers that relate to mineral chemistry:

1. Mineralogist: Mineralogy is the study of chemistry, crystal structure, and physical (including optical) properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.

2. Crystallographer: Crystallography is the experimental science of the arrangement of atoms in solids

3. Geochemist: The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks, water, and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and their interaction with the hydrosphere and the atmosphere.

4. Gemologist: Gemology or gemology is the science dealing with natural and artificial gems and gemstones.[1] It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems

The rock cycle:

Rocks are constantly changing. The rock cycle is a group of changes that occur within the three

types of rock.

In the rock cycle, different conditions produce different types of rocks. Rocks are constantly

changing as they are heated up, cooled down, worn away, and placed under pressure

Sedimentary and igneous rock can change into metamorphic rock

When sedimentary or igneous rocks become buried beneath the ground they become exposed

to intense heat and pressure to form meta rock.

All three types of rocks could be metamorphosed if subjected to appropriate conditions of metamorphism (e.g., heat, pressure, chemically-active fluids). The process of melting is not involved in metamorphism. The grade of metamorphism could be increased (e.g., low-grade metamorphic rocks to high-grade metamorphic rocks) as the conditions of metamorphism are increased.

Igneous and metamorphic rock can change into sedimentary rock.

All three types of rocks could be weathered and eroded. The resulting sediment, once deposited, could be lithified (compacted and cemented) into sedimentary layers.

On earth’s surface, wind and water can break igneous or metamorphic rock into pieces. They

can also carry rock pieces to another place. Usually, the rock pieces, called sediments, drop

from the wind or water to make a layer. The layer can be buried under other layers of

sediment. After a long time the sediments can be cemented together to make sedimentary

rock. In this way, igneous and meta rock can become sedimentary rock.

Sedimentary, & Metamorphic rock can change into igneous rock.

In certain conditions, rock can melt and re-cool to form igneous rock. All three types of rocks could be melted if the temperatures become high enough. Once melting to a molten has occurred, igneous activity has begun. The resulting igneous rocks will depend on the composition of the molten as well as whether it cools slowly inside the Earth (magma) or cools quickly on the Earth’s surface (lava). Igneous Rocks

An igneous rock is formed when magma or lava cools and solidifies

Formed by the cooling and hardening of hot molten rock.

If the molten rock is located within Earth it is called magma.

If the molten rock reaches the surface and exits through volcanoes, it is then referred to

as lava.

Two classifications of Igneous rock;

1) Plutonic (intrusive) – forms from magma.

2) Volcanic (extrusive) – forms from lava.

In the Earth is magma. Magma is buoyant, rises to surface, & sometimes breaks through

When magma reaches Earth’s surface it is called lava

Why should we care?

Igneous rocks make up bulk of Earth’s crust

Earth’s mantle is basically one huge igneous rock

Important rocks economically

Striking landscape features

Igneous rocks that form at the surface are volcanic (extrusive)

Igneous rocks that form deep down are plutonic (intrusive)

To see them, they must be uplifted to surface and softer surrounding rock eroded away

As magma cools, atoms arrange in an orderly crystal structure= crystallization

Classification of Igneous Rocks

Igneous rocks are further classified according to;

Texture: Describes the appearance of an igneous rock, based on the size, shape and

arrangement of interlocking crystals. depends on: how fast/slow magma cools

a. size

b. shape of interlocking crystals

c. arrangement

The texture of an Igneous rock reveals a great deal about the environment in which the rock

cooled and solidified.

Crystal size is the most important factor affecting texture and the size of the crystals is

determined by;

1. Cooling Rate

Molten rock (magma) can cool beneath Earth’s surface.

Large crystals form deep within Earth where magmas may take up to tens of

thousands of years to cool and crystallize.

Therefore, the slower the molten rock cools, the

larger the crystals.

Molten rock (lava) can cool on Earth’s surface.

Fine crystals form on or near Earth’s surface where lava cools quickly in the matter of minutes

to hours.

Therefore, the quicker the molten rock cools, the smaller the

crystals

So…

Fast Cooling-Small or no crystals Slow Cooling Large Crystals

2. Amount of Dissolved Gases

Dissolved gases help the ions in the molten rock to move around and help crystals to form

much faster. This can speed up the crystallization of both magma beneath Earth’s surface and

lava on or near earth’s surface.

Igneous textures

fast cooling magma/lava

forms at or near surface Fine Grained

sometimes holes present, gas vesicles

can’t see individual crystals

also called Aphanitic texture.

forms far below surface

slow cooling

intergrown Crystals Course Grained

larger crystals of uniform size

also called Phaneritic texture.

minerals can be identified with the unaided eye

magma cooled slowly for a while then erupted Porphyritic

minerals crystallize at different temperatures and or rates

this texture results when magma with crystals already formed escape to the surface and cools quickly

forming a fine grained igneous rock with large crystals inside.

this texture is a result of two stages of cooling;

1) slow cooling forming the larger crystals. 2) rapid cooling forming the finer crystals.

very rapid cooling Glassy

ions unable to unite in orderly crystalline structure

forms when gas bubbles escape from molten rock

and are trapped as it cools and crystallizes. Vesicular

this texture can form near the top of lava flows.

minerals can not identified with the unaided eye.

Note: Magmas with high silica content tend to form long chainlike structures impedes ion transport

increases resistance to flow( Viscosity)

In violent volcanic eruptions,

rock fragments

ash

molten blobs Consolidates to form Pyroclastic Rock!

large angular blocks

Mineral Composition: Is the mineral makeup of an igneous rock based on the chemical composition of

the magma. depends on: chemical makeup of parent magma

Igneous compositions

• mainly silicate minerals

• determined by composition of magma from which it crystallized

• magma mainly 8 elements: Si, O, Al, Ca, Na, K, Mg, Fe

The minerals that are present in any igneous rock depends on the chemical composition and the

environment (temperature of the magma) from which the molten rock crystallizes.

N. L. Bowen discovered that different minerals form at different temp.

Bowen also noted that minerals will react with the magma to produce the next mineral in the reaction

series, this is known as Bowen’s Reaction Series

Olivine and Ca-rich plagioclase

feldspar are the first to crystallize

at very high temperatures and

these minerals are often found in

mafic igneous rocks.

Orthoclase feldspar and quartz

crystallize at lower temperatures

and are found in felsic igneous

rocks

Therefore, igneous rocks are classified according to their mineral makeup as Mafic, Intermediate, or

Felsic.

Two major silicate mineral groups: 1.DARK silicates 2.LIGHT silicates

SEE CHART!

Igneous rocks types

Ex: Basalt- Volcanic Gabbro-Plutonic

Mafic: magnesium + ferrum

o High in Mg and Fe.

o Dark and Dense

o Found in Ocean Crust

Composition

contain magnesium and iron rich minerals

form at high temperatures 1200oC

found mainly in oceanic crust

form most volcanic rocks (Basalt)

low percentage of silica, very fluid magmas

forms dark colored minerals, thus rocks are dark color

minerals include; olivine, pyroxene, plagioclase feldspar

Intermediate:

Ex: Andesite-Volcanic

Diorite-Plutonic

Felsic: feldspar + silica (quartz) Ex: Rhyolite, Obsidian, Pumice -Volcanic Granite-Plutonic

High in Si.

Lighter and Less Dense

Found in Continental Crust

contains orthoclase feldspar and quartz (silica)

forms at lower temperatures, approximately 600oC

found mainly in continental crust

form mainly plutonic rocks (Granite)

high percentage of silica, very viscous (thick) magma

forms light colored minerals, thus rocks are light colored

minerals include; orthoclase and plagioclase feldspars, quartz, and muscovite mica

magnesium + ferrum = high in Mg, Fe. Dark, dense

feldspar + silicate = high in Si, lighter, less dense

Classification Chart

Volcanic Igneous Rocks- Examples

Rhyolite:

Quartz and Orthoclase feldspar

Light in color ( < 15% dark minerals)

Microscopic crystals

Andesite:

Amphibole and Plagioclase feldspar

Medium colored ( < 40% dark Minerals

Microscopic crystals

Basalt:

Pyroxene and Plagioclase feldspar

Dark in color ( > 40% dark minerals)

Microscopic crystals

Plutonic Igneous Rocks-examples

Gabbro:

Pyroxene and Plagioclase feldspar

Dark in color ( > 40% dark minerals)

Visible crystals (unaided eye)

Diorite:

Amphibole and Plagioclase feldspar

Medium colored ( < 40% dark Minerals)

Visible crystals (unaided eye)

Granite:

Quartz and Orthoclase feldspar

Light in color ( < 15% dark minerals)

Visible crystals (unaided eye)

CORE LAB #4: “Igneous, Sedimentary and Metamorphic Rocks - Part I: Igneous Rocks”.