intro to Geo
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Examines the material composing earth & seek to understand the many processes that operate beneath & upon itssurface.
To understand the origin of earth and its development through time. It strives to establish an orderly chronological arrangement of the multitude of physical and biological changes that have occured in the geologic past.
nucleus - neutrons - protons - electrons
- transition metals
- noble gases
- lanthanide series
- actinide series
Atomic Mass Number
- The number of protons and neutrons in the nucleus.
Atoms with the same number of protons, but different numbers of neutrons
- (negative Ions)
- which are atoms that gain electrons.
- tend to be larger than cations
- meaning "up", is an ion with more electrons than protons
- (positive Ions)
- which lose electrons.
Three types of Bonds
- Ionic Bond: is the attraction of oppositely charged ions to one another, producting an electrically neutral compond.
- Covalent bound: a chemical bond formed by the sharing of a pair of electrons between atoms.
- Metallic bonds: the valance electrons are free to move from one atom to another so that all atoms share the available valence electrons.
Mineralogist use the term crystal or crystalline in reference to any solid with an ordered, repetitive, atomic structure.
Euhedral crystals vs anhedral
Euhedral crystals are those that are well-formed with sharp, easily-recognised faces.
By contrast, a rock with an anhedral texture is composed of mineral grains that have no well formed crystal faces or cross-section shape in thin section. Anhedral crystal growth occurs in a competitive environment with no free space for the formation of crystal faces
A naturally occurring, inorganic crystalline material with a unique chemical structure.
How do minerals form?
through the process of crystallization, in which molecules and/or ions chemically bond to form ar orderly internal structure.
the players 6
: in 1669 steno's law
or law of constancy of interfacial Angles.
(angels between equivalent faces of crystals of the same mineral are always the same
) ->crystal shape - important for mineral identification.
: sea floor spreading
Aristotles: Greek philosopher - rocks were dreated under the influence of the stars and that earthquakes occured when air crowded into the ground...
Wegener: suspected that the continents might once have been joined.
Democritus: Greek philosopher to make assumption that the milky way existed.
confirming the existence of galaxies other than our own, the Milky Way.
Composition Variation in Minerals
Using sophisticated analytical techniques, researchers determined that the chemical composition of some minerals varies
substantially from sample to sample. These compositional variations are possible because ions of similar size can readily substitute for one another without disrupting a mineral's internal framework.
- ex./ iron-rich olivines have a higher density than magnesium-rich speciments , a reflection of the greater atomic weight of irons compared to magnesium.
- (color-trace elemnts-like quartz)
Structural variations in minerals..example
- exactly the same chemical compositionto have different internal structures and different external forms. POLYMORPHS
- ex./ diamonds and graphite (both made of carbon) but one is stronger because the extreme pressurtes and temperatures produce the compact structure. -ppl can made diamonds out of graphite, but they r not perfect since they are not considered gems.
Physical Properties of Minerals
- the ability to transmit light
Cleavage vs Fracture
Cleavage : is the tendency of a mineral to break
. (minerals tend to break when they are stressed). -weak point [bonds]
- Fracture : Minerals having chemical bonds that are equally or nearly equally, strong in all directions exhibit a property called fracture.
- resembling broken glass.
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