TYPES crust · Sometimes mined for use as

TYPES OF ROCKS

IGNEOUS ROCKS

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– are formed from the solidification of magma, which is a hot (600 to 1,300 °c,
or 1,100 to 2,400 °f) molten or partially molten rock material. The earth
is composed predominantly of a large mass of igneous rock with a very thin
veneer of weathered material.

 

Examples of igneous rocks:

Granite – “the best-known igneous rock”

           

Location:

·       Found at earth’s surface

·      
Stone
mountain, Georgia; Yosemite Valley, California; Mount Rushmore,
South Dakota; Pike’s Peak, Colorado; and white mountains, New Hampshire.

 

Composition:

·      
Forms from the crystallization of magma

·      
Composed mostly of quartz and feldspar with some
amounts of other minerals

·      
A red, pink, gray, or white color with dark mineral
grains visible throughout the rock

·      
Has large grains that can be seen by humans’ naked
eye

·      
A light-colored igneous rock

 

Strengths &
weaknesses:

·      
Is
hard enough to resist most abrasion

·      
Strong
enough to bear heavy loads

·      
Good
enough to overcome weathering and can be brilliantly polished

·      
Needs to be sealed once every once in two years

·      
 

 

Aesthetics:

·      
When polished, granite can be truly appealing

·      
Stain resistant and scratch-proof

·      
Comes with some great antimicrobial qualities

·      
Since granite was composed of different minerals, the colors mixed
uniquely on its appearance

 

Uses:

·      
Rough-cut or polished granite is com monly
used in buildings (interior & exterior), bridges, paving, & monuments

·      
Polished granite can be cut into slabs and tiles
and are used in countertops, tile floors, stair treads

 

Diorite – a composition between that of granite and basalt

           

Location:

·      
New Zealand Occurrences – Northland, Coromandel Peninsula, West Nelson area,
Fiordland, Stewart Island

 

Composition:

·      
Mineral content – plagioclase, amphibole (hornblende) and pyroxene

·      
Silica content – 52%-63%

 

Strengths &
weaknesses:

·      
Durability is like that of granite

·      
Was used as a structural stone by the Inca and Mayan
civilizations of South America

·      
Difficult
to sculpt because of its hardness, variable composition, and coarse grain size

·      
It
is not a favored stone of sculptors

 

Aesthetics:

·      
Has
the ability to accept a bright polish, and it has occasionally been cut into
cabochons or used as a gemstone

 

Uses:

·      
Occurs as large intrusions, dikes, and sills within
continental crust

·      
Sometimes mined for use as a crushed stone

·      
Used as a base material in the construction of
roads, buildings, and parking areas

·      
Used as construction stone; when polished, could be
used as architectural stone

·      
Can be sold as a “granite.”

 

 

Basalt – “fine-grained rock”

          

Location:

·      
Most areas within earth’s ocean basins are covered
by basalt

·      
Basalt are abundant in the Hawaiian Islands

·      
Klamath mountains of northern California and Southern Oregon

·      
Common in some parts of Germany and occur in the United States (as in New
Mexico) and in Libya, turkey, and elsewhere

·      
Leucite-basalts are found in Italy, Germany, Eastern Africa, Australia,
and in the United States

 

Composition:

·      
Has a similar comparison to gabbro

·      
Composed mostly of plagioclase and pyroxene
minerals

·      
Mineral content – groundmass generally of pyroxene (augite), plagioclase
and olivine, possibly with minor glass

·      
Silica (sio2) content – 45%-52%.

Strengths &
weaknesses:

·      
Earth’s most abundant bedrock

·      
Poor shear strength

 

Aesthetics:

·      
Color – dark grey to black

·      
Texture – aphanitic (can be porphyritic)

·      
Some basalts are quite glassy (tachylytes), and many are very
fine-grained and compact

Uses:

·      
Most
commonly crushed for use as an aggregate in construction projects

·      
Crushed basalt is used for road base, concrete aggregate, asphalt
pavement aggregate, railroad ballast, filter stone in drain fields, and may
other purposes

·      
Also
cut into dimension stone

·      
Thin slabs of basalt are cut and sometimes polished for use as floor
tiles, building veneer, monuments, and other stone objects

 

METAMORPHIC ROCKS

– have been
modified by heat, pressure, and chemical processes, usually while buried deep
below earth’s surface

Marble – forms when limestone is subjected to the heat and pressure of metamorphism

  

           

Location:

·      
Italy,
China, India and Spain

 

Composition:

·      
Mostly
composed of the calcite mineral
and contains some other minerals, such as clay, micas, quartz, graphite, and pyrite

 

Strengths &
weaknesses:

·       Easy to carve, and that makes
it useful for producing sculptures and ornamental objects

·       Has a hardness of three on
the Mohs hardness scale.

Aesthetics:

·       Usually a light-colored rock

·       The translucence of marble makes it attractive
for many types of sculptures

·       Can be polished into a
brilliant shine

Uses:

·       Most marble is made into
either crushed stone or dimension stone

·       Used as an aggregate in
highways, railroad beds, building foundations, and other types of construction

·       Used as floor tiles, architectural
panels, facing stone, window sills, stair treads, columns, and many other
pieces of decorative stone

·       Used in monuments, buildings,
sculptures, paving and other projects

 

Slate – a fine-grained, foliated
metamorphic rock that is created by the alteration of shale or mudstone by
low-grade regional metamorphism

             

Location:

·      
Best
slate is said to come from certain countries such as brazil and the United
Kingdom

 

Composition:

·      
Composed
mostly of clay minerals or micas

·      
Can also contain abundant quartz and small amounts of feldspar, calcite,
pyrite, hematite

 

Strengths &
weaknesses:

·      
Stands
up well in contact with freezing water

·      
A
disadvantage is the cost of the slate and its installation in comparison with
other roofing materials

·      
Best material for roofing

 

Aesthetics:

·       Gray in color and range in a
continuum of shades from light to dark gray

·       Also occurs in shades of green, red, black, purple, and brown

Uses:

·      
Also
used for interior flooring, exterior paving, dimension stone, and decorative
aggregate

·      
Roof tiles

 

Quartzite – a non-foliated metamorphic rock

  

Location:

·       Forms during
mountain-building events at convergent plate boundaries

·       Is in folded mountain ranges
throughout the world

 

Composition:

·      
Composed
almost entirely of quartz

 

Strengths &
weaknesses:

·      
Gives
it a hardness of about seven on the mohs hardness scale

·      
Most
physically durable and chemically resistant rocks found at earth’s surface

·      
Resistant
to most chemicals and environmental conditions

·      
A
poor soil-former

·      
Its hardness and toughness cause heavy wear on crushers, screens, truck
beds, and cutting equipment

 

Aesthetics:

·       Usually white to gray in
color

·       Can be a very attractive
stone when it is colored by inclusions

Uses:

·       Used in stair treads, floor
tiles, and countertops

·       Decorative purposes

SEDIMENTARY ROCKS

-formed by the deposition and
subsequent cementation of that material at the earth’s surface and within
bodies of water

 

Shale – a fine-grained sedimentary rock that forms from the
compaction of silt and clay-size mineral particles that we commonly call
“mud”

             

Location:

·      
Can be found almost everywhere on earth’s surface

 

Composition:

·      
Composed
mainly of clay-size mineral grains

·      
Usually contains other clay-size mineral particles such as quartz and
feldspar

 

Strengths &
weaknesses:

·       The rock most often
associated with landslides

·      
Has a very low shear strength – especially when wet

·      
Soft enough to be
cut with a knife and can be very brittle

 

Aesthetics:

·       Usually gray to black in
color due to organic minerals present

·       Can be of different colors
(red, brown, yellow, green)

 

Uses:

·      
Used to produce cement

·      
Used to produce clay

 

Sandstone – a sedimentary rock
composed of sand-size grains of mineral, rock, or organic material

                       

Location:

·      
Found
in sedimentary basins throughout the world

 

Composition:

·      
Contains
a cementing material that binds the sand grains together

·      
Grains
of sand in a sandstone are usually particles of mineral

 

Strengths &
weaknesses:

·      
Durable

·      
Affordable

·      
Water
absorption is very higher than other stone materials 

·       Surface will get scratches
and dents over a period of time

·      
 sandstone
tiles are that its soft compared to granite

 

Aesthetics:

·       Often multicolored stone; are
perfect for decorative touch

·       Colors, patterns, and hues
found in any individual piece are completely unique and different

Uses:

·      
Used as a construction material

·       Often serves as an aquifer
for groundwater or as a reservoir for oil and natural gas

·      
Used
as a raw material in manufacturing

 

 

Limestone – an organic sedimentary rock
that forms from the accumulation of shell, coral, algal, and fecal debris

Location:

·      
Can
be found in the Caribbean Sea, Indian ocean, Persian gulf, gulf of Mexico,
around Pacific Ocean islands, and within the Indonesian archipelago

 

Composition:

·      
Composed
primarily of calcium carbonate

 

Strengths &
weaknesses:

·      
Limestone quarries are visible from long distances and may permanently
disfigure the local environment

·      
Used to make things such as glass and concrete

·      
Some
kinds of limestone are strong, dense rocks with few pore spaces

·      
Stands
up well to abrasion and freeze-thaw

·      
Easier to mine and does not exert the same level of wear on mining
equipment

·      
Does
not perform as well in these uses as some of the harder silicate rocks

·      
 little
maintenance

 

Aesthetics:

·       Can be a beautiful flooring

 

Uses:

·      
Mostly made into crushed stone and used as a construction material

·      
Used
for road base and railroad ballast

·      
Used
as an aggregate in concrete

·      
Dimension stone

·      
Roofing granules

·      
Portland cement

 

References:

https://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/diorite.html

https://geology.com/rocks/granite.shtml

Strength and Beauty: Why Curling Uses Granite for their Stones

https://geology.com/rocks/diorite.shtml

https://geology.com/rocks/basalt.shtml

https://www.britannica.com/science/basalt

Where Does Marble Come From?

https://geology.com/rocks/marble.shtml

https://geology.com/rocks/slate.shtml

https://geology.com/rocks/quartzite.shtml

http://www.softschools.com/facts/geology/slate_facts/389/

https://www.wfm.co.in/what-are-the-advantages-and-disadvantages-of-marble/

https://geology.com/rocks/limestone.shtml

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/limestone/calciumcarbonaterev4.shtml

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/limestone/calciumcarbonaterev4.shtml

Limestone Through the Years

https://geology.com/rocks/sandstone.shtml

http://amstonemasons.com.au/the-benefits-of-using-sandstone-materials-for-construction.html

https://www.thespruce.com/sandstone-flooring-pros-and-cons-1314704