Unit: Earth Materials
Topic 1: Minerals
There are over _3000 different minerals identified in the earth’s crust.
I. _Composition of minerals
a. Most _rocks_ have a number of different minerals in them, and come from
cooled _magma or altered _rock_.
b. The element _oxygen is the most common element found in the earth’s
crust.
c. Silicon is usually found bonded with _silicon_ in most minerals.
d. The most common class of minerals contains the _silicates__, the basis of
which is the silicon-oxygen tetrahedra. Chemical formula SiO4
II. _Rock-forming_ minerals
a. Oxides contain elements, often _metals, and oxygen
b. Sulfides are usually metals and _sulfur_
c. Calcium Carbonates include _calcite_
d. Ferrous minerals contain _iron_(Fe)
III. New York State Minerals
NYS minerals are often _sedimentary_rock minerals.
a. _Garnets_-used as abrasives, found in metamorphic rock in Adirondacks
b. _gypsum, a sulfate, found where ancient seas dried up in central/western
NY
c. _Halite_and other salts, from deposits left by evaporating seas
d. Wollastonite, an evaporite.
IV. The characteristics of all minerals
1. They are all _solid__
2. All minerals have a basic _crystal pattern, or orderly internal pattern of
units
3. All minerals have a definite __chemical composition , which means that
their elements are always in the same ratio
4. They are _inorganic_ (do not come from living things or the remains of
living things).
5. They are _natural, not anthropogenic
V. Mineral Identification
1. Luster- the manner in which the mineral _shines_ in reflected light.
Metallic luster_; the mineral looks like a metal
Non-metallic_ luster; does not look like a mineral.
Ex. Pearly, earthy, dull, glassy
2. Specific gravity- compares the density of the mineral to the density of
water.
3. Hardness is a measure of the minerals __resistance_ to being scratched.
Moh’s scale of _hardness compares minerals to each other. (talc is 1, _diamond_
is 10).
4. Cleavage vs. fracture: description of the mineral’s tendency to break along
definite angles and planes.
_cleavage_ describes clean, patterned breaks, while _fracture_ indicates a lack
of pattern to the break.
5. Streak- the color of the __powdered form_ of a mineral, obtained from
dragging it along an unglazed porcelain plate.
6. Color- color is not always helpful, because one mineral may have trace
amounts of metal and other impurities that will change the color.
7. Other specific tests/indicators such as:
a. sulfur smells
b. calcite (CaCO3) _calcite_ even in weak _acid_
c. _Magnetite is magnetic
d. iron _rusts__
e. halite tastes salty
flame tests can accurately identify minerals and elements
Rocks
Rocks are__conglomerates_ of minerals or simply large samples of one mineral.
1. Usually, rocks are __polymineralic_(have more than one mineral)
2. Rocks are not identified using the tests you used for mineral identification.
3. The __minerals_ in rock help determine the name of the rock.
4. The __origin__of the rock determines which TYPE of rock it is.
Topic 2: Igneous rocks
1. Igneous rocks are called ‘__fire__ __rock__’ because they form from _magma_
or __lava__.
2. Magma is called __’mineral soup’_ because that is where the elements come
together that will form minerals as magma cools.
3. Igneous rocks are called the _parent rock__ of all others.
4. All igneous rocks have _intergrown crystals_, because they form as the
magma cools, and ___________________________________________
_____________________________________ Some crystals are too small to see.
5. Igneous rocks _______ ________________ (see page 6 of ESRT) according to:
a. the _________________________________ of the rock, which is determined by
the magma or lava that forms the rock.
As old rock pushes down into the mantle and melts, it mixes with magma that is
already there, ______________________________________________________.
Over time, different igneous rocks have formed. _______________________
_____________________, and these colors help identify the type of igneous rock.
b. the _____________________________ or grain size of the rock, which is
determined by how quickly or slowly the magma cools to form rock.
c. ________________________________________________________________
Cooling rates and crystal formation
6. In the ______________________________________, the melting points for
common igneous minerals are shown. Minerals with high melting points form
crystals _______________________, while those with low (cool) melting points
forms crystals __________________________.
7. When the magma cools deep below the ground, it is called _________________
or plutonic, and the minerals formed will be ____________________grained.
When the magma cools NEAR the surface, much more ______________________,
the crystals don’t have much time to form and the rock is __________________ or
volcanic, and the minerals will be __________________ grained. Glassy minerals
form _______________________________________.
Magma composition and the 3 igneous families
8. The three main igneous families are _____________________,
____________________and basaltic The families are identified according to the
type of ______________________________ from which they form, which are
characterized by the _______________________________________.
a. The GRANITE family, formed from _____________________ magma, makes up
the CONTINENTAL CRUST, which is low density (_______________) compared
with the ocean crust (_______________).
b. The _________________________ family, formed from _______________
magma, makes up the ocean crust. Its density explains why
___________________________________________
c. The third family is the _____________________________ family, which comes
from magma that is a mixture of both mafic and felsic minerals, therefore its
minerals have characteristics of both granites and basalts.
9. Porphyritic textures refer to igneous rocks that have VARIOUS sized minerals,
like a chocolate chip cookie. This happens when the magma
_______________________ in stages.
10. In summation, Igneous rocks are identified in the lab by comparing their:
_______________________________, which tells you what minerals are in it, and
therefore what magma it came from and the ______________________________,
which indicates whether the rock cooled quickly or slowly (extrusive or intrusive).
Topic 3: Metamorphic Rocks
They are formed:
 When magma ‘____________________ s’ a nearby rock. (at volcanoes,
mid-ocean ridges, intrusions)
 At mid-ocean ridges when _____________________ and sediments mix
with hot gases
 At ____________________ boundaries when rock is ground and deformed
 When mountains form by _________________ , compression
 Overlying sediments exert so much _____________________ they change
the deep rock
1. Metamorphic Rocks form: when ______________________ rocks are
changed (altered) due to heat and pressure.
(If the old rock melts, then it does not become metamorphic, because
melted rock produces magma and igneous rock).
2. Metamorphic rocks are _______________________________ versions of preexisting rock. The minerals _____________________________________________.
Intense metamorphism will change the minerals, too.
3. Metamorphic rock are classified according to:
a. The presence or type of _________________________________, which is seen
by observing the texture of the rock. This must be observed in lab and using
pictures.
b. The second identifier is the __________________________________________
when discussing the ____________________________ rocks. For example, marble
and quartzite look a lot alike, but are made of very different minerals. (the
________________ test identifies marble and a comparison of _________________
shows which is quartzite).
4. Rocks formed by intense pressure ________________________________
____________________________to the direction of the pressure. This often forms
the _____________________ texture.
5. Rocks formed by intense heat are __________________________________
rocks because they are usually bands of rock that are ________________________
due to the presence of nearby lava or magma flows, which partially
______________________ the rock.
7. Contact metamorphic rock are found along igneous ______________________
______________________________________________. Zones of metamorphic rock
usually are ________________________________ igneous rocks and other rocks.