Properties of Minerals

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5 Φεβ 2013 (πριν από 4 χρόνια και 7 μήνες)

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MINERALS

Chemical
composition of the
Crust


Oxygen most abundant
-

46.6%


Followed by silicon and
aluminum


Iron, Calcium, Sodium,
Potassium, Magnesium


The most common minerals
will be composed mostly of
these elements



Silica & silicates

MINERAL vs. ROCK


ROCK


An aggregate of one or more MINERALS
(usually
-

coal, organic)


MINERAL


Solid


Crystalline
-

orderly arrangement of atoms


Naturally occurring


Inorganic


Definite chemical composition


e.g. SiO
2

for quartz; KAlSi
3
O
8

for
feldspar

Atom & Elements


Atoms


Neutral


Nucleus


Proton, neutron



Electron


Ions


Electrical Charge


Molecule
-

e.g. water molecule


Chemical activity


Stable atoms want


positive & negative charges balanced


electron shells full


Ions
-

positive (Cations) and negative (Anions)


Bonding


Ionic


Covalent


Metallic


Van der Waal’s

Element


Atomic number


Number of PROTONS


Isotope


Differing number of
NEUTRONS


Atomic weight


Mass of PROTONS and
NEUTRONS

Crystallinity


3 dimensional orderliness of atoms


Silicon
-
oxygen tetrahedron


Silicate structures


Single
-

e.g.
olivine


Chain



Single chain
-

pyroxene


Double chain
-

amphibole


Sheet
-

e.g. mica, clay


Framework
-

e.g. quartz, feldspar

MINERALS


Crystalline solids


Natural and Inorganic Substances


Definite chemical composition


Can be written as a chemical
formula


Solid solution (within a range)

Important Minerals


Quartz (most abundant)


FELDSPAR Group


Potassium Feldspar

-

Orthoclase


Plagioclase Feldspar


Sodium (Na) Albite


Calcium (Ca) Anorthosite

Important Minerals


PYROXENE Group
-

Augite most
common


AMPHIBOLE Group
-

Hornblende
most common


MICA Group
-

Si + O in sheets


Biotite


Muscovite


CALCITE
-

CaCO
3



Properties of Minerals


Color


Not always reliable (Olivine,
green
; Flourite,
yellow
,
purple
,
green
…)


Ferromagnesian

minerals green or black


Streak
-

powdered form


Luster
-

reflectance of light


Metallic


Nonmetallic


Vitreous or Glassy


Earthy

Properties of
Minerals


Hardness
-

resistance to scratching


Moh’s Hardness Scale


Fingernail = 2.5


Penny = 3.5


Knife/Glass = 5.5


Streak Plate= 6.
5


Properties of
Minerals


Cleavage


Quality (poor, good, perfect)


Number of directions


One
-

e.g.
Mica


Two at right angles
-

e.g.
Feldspar, Pyroxene


Two not at right angles
-

e.g.
Amphibole


Three at right angles (cubic)
-

e.g.

Halite


Three not at right angles (rhombohedral)
-

e.g.
calcite


Four (Flourite) or six (Sphalerite)
-

not common

Properties of
Minerals


Fracture


Absence of cleavage


Irregular fracture


Conchoidal fracture
-

Quartz


Density


Specific Gravity


Some unusual properties


Striations, Magnetism, Taste, Odor, Double
refraction

Chemical tests


Reaction with HCl


Calcite effervesces

Mineral Groups


Silicates


Carbonates


Oxides


Sulfides


Sulfates


Native Elements


Halides

Silicates


Quartz


Feldspar


Plagioclase


Orthoclase


Micas


Muscovite


Biotite


Amphibole (Hornblende)


Pyroxene (Augite)


Olivine

Carbonates


Calcite (calcium carbonate)


Dolomite (calcium
-
magnesium
carbonate)


Both are used as Portland Cement

Oxides


Hematite (iron oxide)


Iron ore, pigment


Magnetite


Iron ore


Corundum (aluminum oxide)


Sapphire, ruby (gemstone)


Abrasive

Sulfides


Galena (Lead sulfide)


Lead ore


Sphalerite Zinc sulfide)


Zinc ore


Pyrite (Iron sulfide)


Sulfuric acid


Chalcopyrite (Copper Iron sulfide)


Copper ore

Sulfates


Gypsum


Anhydrite


Both use in plaster

Native Elements


Gold
-

trade, instruments


Silver
-

photography, conductors


Copper
-

electrical


Platinum
-

catalysts


Sulfur
-

chemicals, pharmaceuticals


Diamond
-

carbon


Gemstone, abrasive


Graphite
-

carbon


Lubricant, pencils

Minerals as Resources


Reserves: Minerals that can be
extracted at a profit under current
economic and technological
conditions


Ores: metallic minerals


Industrial Rocks or Minerals: non
metallic minerals (phosphate)


Aggregates: crushed rock


ROCK CYCLE


Equilibrium


Interrelationships between


igneous rocks


sediment


sedimentary rocks


metamorphic rocks


weathering and erosion