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MINERALSMR. WHITE
ADVANCED CONTENT EARTH SCIENCE
WHO STUDIES THE EARTH’S SURFACE & ITS CHANGING SHAPE?
Geologists!
GEOLOGISTS STUDY…• minerals• rocks• earthquakes• volcanoes• plate tectonics
WHAT IS A MINERAL?• A naturally occurring, inorganic solid that has a crystal
structure and has a definite chemical composition • Must have 5 characteristics:
• Naturally occurring• Inorganic • Solid• Crystal structure• Definite chemical composition
NATURALLY OCCURRING• Minerals must occur naturally• Cement, brick, steel, & glass
are not minerals because they are manufactured by man
INORGANIC• It cannot arise from materials that were
once part of a living thing• Ex: Coal is organic which comes from the
remains of plants & animals• Coal is not a mineral
SOLID
Must be solid with a definite volume & shape
CRYSTAL STRUCTURE
The mineral must have particles that line up in patterns that repeat over & over again
DEFINITE CHEMICAL COMPOSITION• The mineral contains certain
elements in definite proportions• Almost all minerals are
compounds, 2 or more elements combined
• Ex: Quartz-made of 1 atom of silicon to every 2 atoms of oxygen
HOW ARE MINERALS IDENTIFIED?• Each mineral has its own set of properties used to identify it• Mineral Tests include:
• Color• Hardness• Streak• Luster• Density• Crystal Systems• Cleavage & Fracture• Special Properties
COLOR
• The color of a mineral is an easy identifiable test
• Color is not a reliable test for identifying minerals
HARDNESS• Mohs Scale is used to test the
mineral’s hardness• The scale ranks 10 minerals
from softest to hardest• A mineral can scratch any
mineral softer than itself• To test hardness we use items
of known hardness to try and scratch the mineral sample
STREAK• The streak of a mineral is
the color of its powder left behind when scratched on a streak plate
• Often times the mineral color & the streak color are different
LUSTER• Luster describes how a mineral reflects light from
its surface• Ex terms used to describe luster:
• Glassy• Shiny• Earthy• Waxy• Pearly
DENSITY• Each mineral has a characteristic density• Density = mass ÷ volume• It is shown as mass per cubic volume• Use a balance to get the mass of the
mineral• Place the mineral in water to get the
volume• Divide mass by the volume
DENSITY• Density is the mass in a given
space• A balance is used to determine
the mineral’s mass & a graduated cylinder is used to determine its volume=DENSITY
• D=M/V
CRYSTAL SYSTEMS
Six crystals systems, based on the number of
angles of the crystal structures, are used to
identify minerals
6 CRYSTAL SYSTEMS
CLEAVAGE & FRACTURE• The way a mineral breaks can help to identify it• Cleavage-a mineral that splits easily along flat
surfaces. For Example: mica•Fracture-a mineral that splits apart in an irregular
way. For Example: quartz
CLEAVAGE OR FRACTURE?
SPECIAL PROPERTIES
Minerals can also be identified by special features
Ex: Fluorescence-minerals that glow under ultraviolet light
SPECIAL PROPERTIES• Optical (visual) properties- Calcite
bends light to produce a double image
• Magnetism- Magnetite attracts iron staples.
• Reactivity- Aragonite reacts chemically to acids.
• Radiation- Uranium emits radon gas.
HOW DO MINERALS FORM?1. They crystallize from melted (liquid) materials like magma & lava2. They crystallize when certain materials are dissolved in water
HOW ARE MINERALS USED?Minerals are used in everything from talcum
powder to brilliant gemstones
ORE- A MINERAL OR ROCK IS AN ORE IF IT CONTAINS A
USEFUL SUBSTANCE THAT CAN BE MINED.
Hematite is an iron ore.
Bauxite is an aluminum ore.
What is an ore?
TALC
• talcum powder• crayons• paints• soaps
QUARTZ• Glass making• Electronic equipment• Watches• Tv’s/Radios• Most common mineral
KAOLIN• China/pottery• Paper• Medicines• Kaolin is mined in
South Georgia
GYPSUM
• Cement• Stucco
CALCITE
• Photography• Medicines
GRAPHITE
• Pencils• Tennis rackets
FELDSPAR
• Pottery• Glass• Porcelain
HALITE
• Table salt• Food preservatives
FLUORITE• Toothpaste• Plastics
WRITE DOWN ANY QUESTIONS THAT YOU HAVE AND WE WILL ANSWER THESE
ON MONDAY!