minerals. naturally occurring inorganic crystalline solid (atoms are arranged in a repeating...
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Minerals
Minerals
Naturally occurring Inorganic Crystalline solid (atoms are arranged in a
repeating pattern) Definite chemical composition
Why do we study Minerals? Starting point for all geologic formations and
activity Rocks and molten rock (lava, magma) are what
shape the surface of our planet
Minerals Can Be Elements or Compounds
Single elements that are also minerals are called native elements (ex: copper)
Most minerals are compounds made from different elements
8 most common elements: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium,
Potassium, Magnesium
How Minerals Form
1. The cooling and hardening of magma
2. When water containing dissolved ions evaporate
3. Sustained pressure, heat, or chemical action can change minerals into other minerals
Mineral’s Crystalline Structure All minerals are crystalline (all of their atoms are
arranged in a repeating pattern)
The atoms pattern can be used to identify a mineral
Crystal system controls the way a mineral forms and breaks
Crystal System Models
1. Color the shapes according the colors listed below. A:Red B: Blue C: Green D:Yellow E: Orange F: White
2. Cut them out
3. Fold them along all the black lines
4. Put glue on the small tabs and CAREFULLY glue them into the shapes they fold into.
5. You will need the small images of the crystals. Cut them and secure them in a safe place. Do NOT lose them!
The 6 Crystal Systems: #1 Cubic System 3 axes of equal length
that intersect at 90 degree angles
Example- Halite (Rock Salt)
The Six Crystal Systems #2 Orthorhombic System Three axis of different
length that intersect at 90 degree angles
Examples: Sulfur, Topaz
The Six Crystal Systems #3 Tetragonal System Three axes, 2 of the
same length, one that differs
Examples: Wulfenite
The Six Crystal Systems #4 Triclinic System Three axes of
unequal length that intersect at oblique angles.
Example: Turquoise
The Six Crystal Systems #5 Hexagonal System Three horizontal axes that
are the same length, and a vertical axis that is longer then the horizontal axes.
Example: Quartz Graphite
The Six Crystal Systems #6 Monoclinic System Three unequal axes,
two intersect at 90 degrees, the third is oblique to the other two
Example: Gypsum, Borax
Physical Properties Color: The color as it appears to the naked eye
Not effective in identifying minerals Some are similar in color Others can have their color changed Some come in multiple colors
Physical Properties Streak: the color of the powder a mineral leaves
after rubbing it on a streak plate.
More effective than color because the streak is often different than the color, and can be distinct to the mineral
Properties Cont’d Luster: the way a mineral shines and reflects light
Metallic Luster: Shines like a polished metal Ex: Pyrite, Galena, Hematite, Magnetite
Non-Metallic: Anything non-metallic. Ex: Quartz, Fluorite, Sulfur, Opal
Mohs Hardness Scale Hardness: A mineral’s resistance to being
scratched
Moh’s Hardness Scale: The hardness of minerals relative to each other/scratching implements.
These are labeled 1-10, 1 being the softest, 10 the hardest.
Mineral Tools
1.Talc Fingernail
(2.5)2.Gypsum
3.Calcite Nail
(Avoid the point)
(4.5)
4.Fluorite
5.Apatite Glass
(5.5)6.Feldspar
7.Quartz Streak Plate (5-8)8.Topaz
9.Corundum
10. Diamond
Cleavage Cleavage: the tendency of
a mineral to split along a certain plane or planes
Not all minerals have cleavage
We describe it in numbers of planes and angles of intersection
Fracture Fracture: When minerals don’t
break along certain planes
3 KINDS Conchoidal: Shell Like and
smooth Hackly: Jagged Edges Fibrous: Breaks into strands
Special Properties Texture: Having a unique feel to the touch (talc,
graphite)
Effervescence: Reacts by bubbling when exposed to hydrochloric acid (calcite, dolomite)
Taste: What does it taste like?… Duh… (Halite/Rock Salt)
Special Properties Cont’d Smell: (Sulfur smells like eggs)
Magnetism: Mineral has magnetic properties (Magnetite)
Density: the amount of water it displaces (Metallic lusters are generally denser)
Phosphorescence: Does it glow under black light? (Fluorite)
Today = Finish Dummies Guide
Make sure all information is complete.
All charts and test are complete.
Accurately identify minerals A, B, C, D using your notes and classification chart.
The Silicates
Silicates: Compound of the elements Silicon and Oxygen
90% of minerals are silicates
Form from the cooling of Lava/Magma
The Si and O join to form Silicon-Oxygen Tetrahedrons
Silicate Minerals:
Quartz: Multiple forms of quartz
(rose, amethyst, crystal) Conchoidal Fracture Mohs Hardness: 7 Luster: Glassy
Silicate Minerals Continued…
Feldspar: The most abundant family
of minerals in earth crust Plagioclase or Orthoclase
Feldspar 2-3 directions of cleavage Mohs Hardness: 6 Luster: Pearly
Silicate Minerals Continued…
Mica 2 Types Muscovite mica (white
mica), and Biotite mica (black or brown)
One distinct Cleavage (makes long sheets)
Mohs Hardness: 2.5 Luster: Pearly
Silicate Minerals Continued…
Talc The softest mineral,
talcum powder is pure ground up talc
1 direction of cleavage Mohs Hardness: 1 Luster: Pearly/Oily
Silicate Minerals Continued…Olivine: Olive green silicate Belongs to a family where
silicates bond to metal ions, ocassionally found in meteors
Conchoidal Fracture Mohs Hardness: 6.5 Luster: Glassy
Silicate Minerals Continued…
Garnet: A very common
gemstone Conchoidal Fracture Hardness: 6-7.5 Luster: Vitreous to
resinous
Other Mineral Groups
Carbonates 2nd most common mineral group Contains the elements carbon and oxygen
and one or more other metallic elements EX. Calcite, Dolomite
Carbonate Minerals
Calcite: Composed of Calcium
Carbonate (CaCO3)
CALCITE FIZZES WITH ACID!!!
3 directions of cleavage Mohs Hardness: 3 Luster: Glassy
Carbonate Minerals
Dolomite: Composed of a Magnesium
Carbonate (MgCO3) 3 directions of cleavage Mohs Hardness: 3.5 to 4.0 Luster: Glassy/Vitreous
Halides: Contain a halogen ion plus
one of more elements
Formed from salt water evaporation
EX. Halite, Fluorite
Other Mineral Groups
Other Mineral Groups
Sulfides/ Sulfates:
Contain the element sulfur and one other element, often metallic
EX. Gypsum, Pyrite
Bellringer Quiz
1. ______The way a mineral reflects or “reacts” to light 2. ______A mineral’s resistance to being scratched 3. ______ Includes taste, effervesence, smell, phosphorescence 4. ______Describes the way minerals naturally split 5. ______The color of a minerals powder when rubbed across an
unglazed porcelain plate 6. ______When minerals don’t break along cleavage lines 7. ______Considered to be a not-reliable way to I.D. minerals 8. Define mineral! 9. Why are color AND luster unreliable for IDing minerals?
Other Mineral Groups Oxides: Contain oxygen and one
or more other element usual a metal.
Can form from magma or from weathering
EX. Hematite (Rust), Corundum, Magnetite
Other Mineral Groups
Native Elements:elements that exists in relative pure forms
Many form from hydrothermal solutions
EX. Diamond and Graphite (carbon), silver, gold, copper, sulfur
Mineral uses Talc – talcum powder Quartz – Glass, Sand Paper, Amethyst Gems Diamond – Gems, drills Beryl – Emerald Gems Corundum – Ruby Gems Gypsum – Drywall Halite – Rock Salt Copper – Wire, Jewelry, etc… Galena - Lead ore
Bellringer Picture
Iron Oxide and Sulfates
Oxides
-A mineral consisting of a metal element combined with oxygen
Sulfates
-A mineral consisting of a metal element combined with sulfur
Iron Oxide Minerals
Hematite The most common Iron
Oxide mineral Red to brown streak on
streak plate Mohs Hardness: 5 to 6 Luster:Metallic (sometimes
earthy if it gets worn down)
Iron Oxide Minerals
Magnetite: A black magnetic iron oxide Mineral has magnetic
properties Black streak Mohs Hardness: 5.5 to 6.5 Luster: Metallic to Dull
Iron SulfidesPyrite: An Iron Sulfide (Fe3SO4) Occurs in 6 and 12 sided
crystals “Fools Gold” Greenish-Black streak Mohs Hardness: 6.0 Luster: Metallic
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