GSC 111 Lecture 5: Minerals and Rocks
13 Jan 2017
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Minerals and Rocks
1. Minerals- naturally occurring inorganic solid element or compound with a particular
chemical composition or range of compositions and a characteristic internal structure
a. 4000 known minerals on Earth
b. Ex: Gold
i. Single element
c. Ex: Halite
i. Compound made up of sodium and chloride
d. Each have characteristic internal structure
2. How they form
a. Liquid state crystallization
i. As magma cools, mineral forms
ii. If we have water with ions, it can evaporate and halite crystals form as it
evaporates
b. Solid state crystallization
i. Result of higher temperature or pressure during metamorphism
3. Minerals each have distinct properties
a. Color
b. Cleavage planes
i. Based on internal structure, minerals will break (cleave) in various
patterns
ii. Ex: salt breaks into perfect squares
c. Crystal forms
i. Shape that the mineral grow when left to grow freely
d. Specific gravity
e. Hardness
i. Diamond is hardest
ii. Moh-hardness scale to rate hardness from 1 to 10
iii. Talc is soft
f. Luster: how shiny something is
g. Taste
h. Reaction with acid
4. Major groups
a. Silicates
i. Have silicone and oxygen
ii. Cation mixed with silicate
iii. One of biggest and most important groups
iv. Two types
1. Mafic- have high concentration of magnesium and iron
a. Dark
b. Cool and form in magma chamber first
2. Felsic- have high concentration of sodium, potassium, calcium,
aluminum
a. Light
b. As rock cools further, comes felsic
v. Olivine is first to form when magma cools in Bowen’s Reaction Series
