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ESS102H1 Study Guide - Rhyolite, Conoscopic Interference Pattern, Biogenic Substance


Department
Earth Sciences
Course Code
ESS102H1
Professor
Grant Henderson

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ESS221 Study Notes Condensed
Lecture 1 & 2: Mineral Properties
Mineral Definition:
-Naturally occurring
-Made Inorganically (mostly)
-definite but not fixed chemical composition
-solid crystalline structure
-homogenous substance
*defracts X-rays
Naming Minerals
Family > Group > Species > Series > Polymorphs > Varieties
Family: group related by composition.
eg. Tectosilicates
Group: related by similar atomic structure.
eg. Quartz group
Species: type of group
eg. alpha or beta quartz
Series: same structure, different composition
eg. Olivine: forsterite Mg2SiO4 and fayalite Fe2SiO4
Polymorph: different structure, same formula
eg. stishovite, coesite
Variety: same mineral, with distinct physical properties
eg. amethyst, rose quartz
Silicate Minerals:
SiO4 4-
Si2O7 6-
Si6O18 12-
Si2O6 4-
Si4O11 6-
Si2O5 2-
SiO2

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ESS221 Study Notes Condensed
Diagnostic Information
Idiochromatic: color by essential elements
Allochromatic: color by trace or minor elements
Moh’s Scale:
Logarithmic.
Talc, Gypsum, Calcite, Fluorite, Apatite, Orthoclase, Quartz, Topaz, Corundum, Diamond
2.2 fingernail, 3.2 copper penny, 5.5 glass plate, 6.5 steel file, 7.0 streak plate.
Cleavages:
-basal: 1 direction. eg. micas
-feldspar cleavage: 2 at right angles
-cubic: 3 at right angles. eg. galena
-calcite cleavage: 3 at non right angles
-octahedral: 4 directions. eg. fluorite, diamond
-6 directions: eg. sphalerite
-prismatic: multiple directions parallel to one cleavage.
Parting: breakage from an unusual point of weakness in the crystal due to twinning plane
or exsolution.
Sheen:
adularescence - reflection from microscopic inclusions
schiller - reflection from inner layers
iridescence - reflection from interference of inner layers
play of color - diffraction of light through spheres of SiO2 in Opal
Other:
specific gravity: eg. Galena
taste, smell: Halite, Sulphur
feel: graphite
magnetism: magnetite
reaction with HCl: carbonates
fluorescence: wolframite
Lecture 3: Earth Chemistry
crust - 36km from continents, 10-13 from ocean. Upper = sed. 95% ig rock. 10 miles down.
upper mantle - 36-410km. Olivines + pyroxenes + garnet
transition zone - 410-660km spinels + majorite
lower mantle - 660-2600km. silicate perovskite + ferropericlase
D’’ layer - 2600-2900km. post perovskite
outer core - 2900-5100km. liquid iron allow
inner core - 5100-6400km. solid iron.
Earth Minerals
116 elements found in nature. 8 make up 99% of crust: O, Si, Al, Fe, Ca, Na, K, Mg
-most crustal are O based. Some elements are concentrated in specific minerals (eg. Zr in
Zircon ZrSiO4)
-39% plag, 12% alkali feld, 12% quartz, 11% pyroxenes, 8% non silicates. . . . .

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ESS221 Study Notes Condensed
Solid Solution
ions substituting for each other in a mineral. Rarely find pure mineral states. Occurs as
size of ions and site change composition, as well as temp/press changes.
Lecture 4: Mineral Chemistry and Bonding
Covalent > Ionic > Metallic > Van Der Waal’s
Ions can form from light, heat, and electron exchange between atoms.
HCP: Hexagonal closed packing - ABABABABAB
CCP: Cubic closed packing - ABCABCABCABC along [111]
Pauling’s Rules
1: Coordination Principle:
Large radius atoms pack around a small radius atom in as tight a configuration as
possible such that the small atom never rattles around in the space. The large radius
atoms are always in contact with the small radius atom. Based on Radius ratios and angles
from them.
2: Electrostatic Valency Principle:
Bond strength (e.v.) = ZC/C.N
In a stable crystal structure, the total strength of the valency bonds that
reach an anion from all the neighbouring cations is equal to the charge of
the anion
Eg. Mg2+O6: SMg-O = 2/6 = 1/3
Eg. Si4+O4: SSi-O = 4/4 = 1
3: Sharing of Polyhedral Elements I
The more corners that are shared between two polyhedrons, then the closer together the
cations are. This destabilizes the structure because of cation-cation repulsion.
4: Sharing of Polyhedral Elements II
In a crystal containing different cations, those of high valence and small coordination
number tend not to share polyhedral elements with each other.
5: Principle of Parsimony
The number of essentially different kinds of constituents in a crystal tends to be small. Very
few types of contrasting cation-anion sites.
Lecture 5: Lattices and the Unit Cell
lattice = grid /w motifs (single unit. eg. ion, atom) repeated regularly *which can be packed
in a limited number of ways. They can be translated with an arbitrary origin.
2D unit cells: primitive or non-primitive (2 points +)
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