Download Dynamic Earth Chapter 4-Highlights Rocks and Minerals Highlights

Dynamic Earth
Chapter 4-Highlights
Rocks and Minerals
A. Highlights for Section 1 pages 79-87
 Natural occurring, inorganic solid that has a definite
chemical composition and crystal shape is called a mineral.
o Must be inorganic—not formed from living things
o Quartz is a mineral
o Atoms are arranged in a definite, repeated pattern—
crystal
 Minerals have certain physical properties
o Color—easily observed
o Luster—way mineral reflects light from its
surface…either metallic or dull luster
o Hardness—ability of a mineral to resist being
scratched – Mohs Hardness Scale
 If unknown mineral is scratched by a known
mineral, it is softer than the known mineral
 If unknown mineral scratches the known mineral,
it is harder than that mineral
 If they do not scratch each other, they have the
same hardness
o Streak—color powder scraped off
o Density—amount of matter in a given space
o Crystal shape—six basic shapes
o Cleavage—mineral splits along smooth surface
o Fracture—break along rough jagged surface
I. Highlights for Section 2 pages 88-91
 Ores are minerals from which metals and
nonmetals can be removed in usable amounts
 Metals are elements that have shiny surfaces
and are able to conduct electricity and heat
o During smelting—ore is heated so that the
metal can be separated
o Iron used in making steel—copper for
wire—aluminum for cans
 Nonmetals are minerals that have dull surfaces
and add are poor conductors of electricity and
heat
o Sulfur used for matches and meds and
fertilizers
 Some minerals are hard-durable-beautiful
o Cut and polished for jewelry
o Gemstones
 Rarest—diamonds, rubies, sapphires,
emeralds are precious stones
 All other gemstones are
semiprecious—zircons, turquoises
M. Highlights for Section 3 pages 93-97
 Rock is hard substance composed of one or more
minerals—rocks are placed in three main groups
o Igneous rocks—were originally hot, fluid
magma within Earth
o Sedimentary rocks—are formed from particles
that have been carried along and deposited by
wind and water
 Sediments include bits of rock in the form
of mud, sand, pebbles---later pressed
together to form rocks
o Metamorphic rocks—are formed when
chemical reactions, tremendous heat, or great
pressure change existing rocks into new kids
of rocks.
 Rocks that form the Earth’s surface are subject to
change
o Continuous changing of rocks from one kind to
another over long periods of time---rock cycle
 Has no definite sequence
R. Highlights for Section 4 pages 97-100
 Igneous rocks are classified according to their
composition and texture
o Composition
 Way magma cools and where it cools
determines the size of mineral
crystals
 The longer it takes magma to
cool, the larger the crystals that
form.
o Texture
 Glassy and fine grained rocks from
lava on the Earth’s surface
 Course grained rocks from magma
within the Earth
 Rocks formed from lava are called extrusive or
volcanic rocks.
 Igneous rocks formed from deep within the
Earth are called intrusive rocks.
W. Highlights for Section 5 pages 101-104
 Sedimentary rocks are placed into 3 main
categories according to origin of materials from
which they are made
o Clastic rocks—sedimentary rocks made from
fragments of previously existing rocks
 Further classified according to size and
shape of fragments in them
 Example---sandstone
o Organic rocks—come from organisms—formed
directly or indirectly from material that once
was living
 Example---limestone
o Chemical rocks—when a sea or lake dries up—
leaving large amounts of minerals that were
dissolved in water
 Example---rock salt
EE. Highlights for Section 6 pages 105-107
 Already existing rocks are buried within
the Earth, tremendous heat, great
pressure, and chemical reactions may
cause them to change into different rocks
with different textures and structures--changing of one type of rock into another
is called metamorphism
o Pressure within Earth tends to
squeeze mineral crystals of rock
together—forming denser materials
o Slate formed from shale
o Gneiss formed from granite