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

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