rocks & minerals
TRANSCRIPT
Unit 2Unit 2
•Rocks and MineralsLithosphereLithosphere
OK – so here’s the real introduction to OK – so here’s the real introduction to Rocks & MineralsRocks & Minerals
What is a Mineral?What is a Mineral?
• Solid Earth Materials
• Naturally Occurring
• Inorganic
• Definite Chemical Formula
• Definite Crystal Structure
Minerals Minerals
ESRT Pg 16
Minerals can beidentified bytheir chemicaland physicalproperties.
What is a
Mineral?
Minerals Fist List
High Five!!
Solid, Earth Material
What does that mean?!?!?!
--Not a gas or a liquid
--Has a definite shape and volume
QUESTION?Is oil a mineral??
Answer…No, because it is a liquid.
Naturally O
ccurringWhat does that mean?!?!?!
--Not man-made
Inor
gani
c
What does that mean?!?!?!
--Not formed from living things or the remains of living things
--NON-LIVING!!
EXAMPLES
1. Coal is NOT a mineral because it comes from plants.2. Amber is NOT a mineral because it comes from tree sap.3. A pearl is NOT a mineral because it comes from oysters.
Def
inite
Che
mic
al F
orm
ula
What does that mean?!?!?!
--The elements that make up the minerals are combinedin definite proportions
--Chemical formula can be found on page 16 ofESRT.
EXAMPLES-Gold (Au)-Pyrite (FeS²)-Graphite (C)-Diamond (C)
Definite
Crys
tal Stru
cture
What does that mean?!?!?!
--Atoms are arranged in a repeating pattern
--Each mineral has a different INTERNAL ARRANGEMENT OF ATOMS that gives it distinct physical and chemical properties
What does that What does that mean?!?!?!mean?!?!?!
Defini
te C
rysta
l Stru
cture
QUESTION
How does the mineral graphite,which is soft have the same chemical formula as diamond,which is the hardest mineralin the world?
ANSWER
Because their internalarrangement of atoms are different
How are Minerals
Identified??
Fill in the spiders legs as we go!!
ESRT Pg 16
Minerals can beidentified bytheir chemicaland physicalproperties.
Color
How are Minerals Identified??
--Least useful for identification
--One mineral can come in many colors
EXAMPLE: --Hematite: Comes in black, red and brown
How are Minerals Identified??
1. Some minerals are always the same color
2. Some minerals can have many colors
Smoky QuartzRose Quartz Quartz
Sulfur
Colors can vary as a result of…Colors can vary as a result of…
A. Chemical Impurities– Cobalt compounds tend to be pink, purple, or blue
Manganese—tends to produce pink colors
Colors can vary as a result of…Colors can vary as a result of…
B. Oxidation—exposure to air and water changing the color of the mineral.
Ex. Rust
--Iron is the dominant coloring agent in rocks and soils
How are Minerals Identified??
Streak
--the color of a mineral when it is finely powdered
--determined by rubbing the mineral on a piece of tile
Hematite has a reddish-brown streak.
How are Minerals Identified??
Luster
--describes how a mineral appears to reflect light
There are 2 categories in which a minerals luster can fall…
Metallic OR Non-Metallic
How are Minerals Identified??How are Minerals Identified??
A. Metallic– reflects light like metal (shiny)
GalenaGraphite
Pyrite
How are Minerals Identified??How are Minerals Identified??
B. Non-Metallic—any mineral which DOES NOT exhibit shiny metallic characteristics
Ex. Quartz
Metallic or Non-Metallic??Metallic or Non-Metallic??
Non-Metallic
Mica
Pearly luster
Metallic
Magnetite
Metallic or Non-Metallic??Metallic or Non-Metallic??
Non-Metallic
Pyroxene
Dull luster
How are Minerals Identified??
Hardness
--Resistance of a mineral to being scratched
--Moh’s Hardness Scale—compares the hardness of the mineral to 10 reference minerals.
How is Hardness Determined??How is Hardness Determined??
Softest
Hardest
The scale consists of number 1 through 10; 1 being the softest and 10 being the hardest. Each number represents a different mineral- each harder than the previous. The 10 minerals are to the left.
How is Hardness Determined??How is Hardness Determined??
Several common household items have a fixed hardness, and can be used to test for hardness.
-Fingernail = 2.5-Copper penny = 3-3.5-Nail = 4.5-Knife blade = 5.5-Glass = 5.5-Steel file = 6.5-Streak plate = 7
What Determines Hardness?What Determines Hardness?
--Hardness is determined by a minerals internal arrangement of atoms.
Ex. Diamond vs. Graphite-Diamond has hardness of 10 and graphite is ranked between 1 and 2. Diamond is about 40 times harder than graphite due to the way the atoms are arranged.
--Hardness is the best property to use to identify a mineral.
How are Minerals Identified??
Cleavage or
Fracture
Cleavage—when a mineral breaks along a flat, smooth surface
Examples of Minerals that show CleavageExamples of Minerals that show Cleavage
Mica exhibits basal cleavage.
Galena exhibits cubic cleavage.
What Determines Cleavage?What Determines Cleavage?
A minerals internal arrangement of atoms!!
How are Minerals Identified??How are Minerals Identified??
Cleavage or
Fracture
Fracture—When a mineral breaks along irregular rough surfaces.
EX. Quartz
How are Minerals Identified??
Density or Heft
--The amount of matter in a given space (mass/volume)
Depends on…
-kind of atoms which make up the mineral
-how the atoms are arranged in the crystal lattice
How are Minerals Identified??
Crystal Shape
--Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming
How are Minerals Identified??
Special Properties
-Magnetism (Magnetite)
-Glowing under ultraviolet light (Fluorite)
-Salty taste (Halite)
-Smell (Sulfur)
-Reaction to HCl (Calcite)
IMPORTANT!IMPORTANT!
• Remember on the Regent’s Exam most of the information about the mineral in a question will be given to you or you will observe from the diagrams on the Exam. Use them to your advantage. Make sure you know the basics about mineral identification and observe carefully…….
• USE PAGE 16 OF THE ESRT
How are rocks How are rocks formed?formed?
Rocks are classified Rocks are classified by their process of by their process of
formation.formation.
LithosphereLithosphere
Igneous
Sedimentary
Metamorphic
sedimentssediments and mineralsminerals are compacted
and cemented With dissolved minerals
ClasticClastic – pieces of other rocksCemented into
rock
ChemicalChemical – Evaporites
From seawater
Organic/Bioclastic Organic/Bioclastic Remains of plantsOr animals whichAre transformed
Into rock
ROCKSROCKS
Sedimentary RocksSedimentary RocksForm whenForm when
Minerals
Clastic
And
Are cemented together
The 3 types of sedimentary rock are
SEDIMENTS
Chemical Organic
pg 6 in your notes
Texture and Grain SizeTexture and Grain Size
• Texture is described based on grain size, grain shape, and grain pattern.
• Most rocks are made up of tiny particles of minerals or other rocks, which are called grains.
• A rock’s grains give it its texture
•Through the process of
, rock is loosened and carried away with wind and water by
. The sediment then settles out of the wind and water during depositiondeposition. The sediment begins to settle out and form
.
Origins of Sedimentary RockOrigins of Sedimentary Rock – Draw an arrow from “CLASTIC”
weatheringweathering
erosionerosion
layerslayers
compactioncompaction
CementationCementation
As the layers stack up, they become heavier until the weight squeezes the layers together during
.
Dissolved minerals act as glue in a process known as .
Earth Science Reference Table Page 7Earth Science Reference Table Page 7
• This is a sample of breccia, a coarse-grained sedimentary rock with coarse, angular fragments.
• This is a sample of sandstone, a sedimentary rock that formed from sand grains.
ChemicalChemical
• Formed when minerals dissolved in water, precipitate out and form crystals on the sea floor – Includes evaporites.
Earth Science Reference Table Page 7Earth Science Reference Table Page 7
Organic (bioclastic) – rocks formed from the remains of plants and/or animals that undergoes a transformation into rock.
• This is a sample of limestone, a sedimentary rock made of calcium carbonate that formed under water indirectly from the remains of tiny marine organisms.
Coal FormationCoal Formation
Grand CanyonGrand Canyon
Rocks classified on the basis of their
formation (how they are made)
Monomineralic Polymineralic
Composed of 1 mineral
EX:
Limestone - Calcite
Composed of many minerals
Ex: Granite
Feldspar, quartz, hornblende
Igneous RockIgneous Rock• Igneous rock forms
when magma or lava
COOLSCOOLS SolidifiesSolidifiesCrystallizesCrystallizes
hardenshardens
CrystallizationCrystallization
TEXTURE
Intrusiveor Plutonic
Extrusive or Volcanic
Coarse Grained large crystalsNon-Vesicular
(no gas bubbles)
Magma
UndergroundSlow cooling
Fine Grained (small crystals)Glassy
Gas Pockets (vesicular)
LAVA
Above groundFAST cooling
Granite vs. ObsidianGranite vs. Obsidian
Extrusive
Intrusive
Igneous RockIgneous Rock
Mineral Composition
FELSICFELSICLow density
MAFICMAFICHigh Density
Rich in AluminumRich in Aluminum Rich in IRON &Rich in IRON &MagnesiumMagnesium
Light Colored
Rocks Called
Dark Colored
Rocks Called
Igneous Rock chart found on Igneous Rock chart found on page 6page 6 of of Reference Tables Reference Tables
High light it in your ESRT!High light it in your ESRT!
Rock characteristics can be determined using this chart
Mineral content can also be determined using this chart
Ho
w to
read it!
Ho
w to
read it!
Metamorphic RocksMetamorphic Rocks
ConditionsConditions that cause rocks to that cause rocks to
undergo metamorphism undergo metamorphism includeinclude::
• Deep burial and pressure or hot contact zones
• Metamorphic rocks are often found in mountainous regions
You’ll have to add this to your notes on page 8
Heat
Pressure
Chemical due to Contact
Metamorphic rocks are characterized by:
• Increased DENSITY
• NEW Minerals
• BANDING
Metamorphic Rocks – Metamorphic Rocks – formed when a rock formed when a rock
is changed byis changed by
Metamorphic Rocks are classified by the arrangement of their:
MINERALSMINERALS
Into two types of metamorphic Into two types of metamorphic rocks called:rocks called:
Non - Foliated
Foliated and
Bottom of Page 7 of ESRT Bottom of Page 7 of ESRT
Where the minerals grains areWhere the minerals grains are
Not aligned and appear MASSIVE
Squeezed and curved or
folded
Foliated (think Foliated (think FOLD)FOLD)
Mica SchistMica Schist
GneissGneiss
Increased HEAT Increased HEAT and PRESSUREand PRESSURE
Non-FoliatedNon-Foliated
• Massive Massive Metamorphic Metamorphic rocksrocks
Metamorphic Rock Chart Metamorphic Rock Chart (page 7 Earth Science (page 7 Earth Science Reference TableReference Table
• Increasing metamorphic change occurs with increasing temperatures and pressures.
• If the melting point is reached, the change is no longer metamorphic, and igneous rocks are formed.
The Rock CycleThe Rock Cycle(Page 6 of Earth Science Reference Table)(Page 6 of Earth Science Reference Table)
• The Rock Cycle describes the continually changing structure of rocks.
Distribution of Rocks in the U.S.Distribution of Rocks in the U.S.