Chapter 5 - Minerals Flashcards
Crystal lattice
The imaginary framework representing Ye arrangement of atoms
To be a mineral it must be
Naturally occurring, solid, formed by geologic processes, definable chemical composition, orderly arrangement of atoms. Pg 148 in organic
Crystalline solid
A material in which atoms are fixed in an orderly pattern
A glass
Atoms, ions or molecules are arranged in a semi chaotic way. Pg 124
What is a crystal?
A single, continuous piece of a crystalline solid blinded by flat surfaces called Crystal faces that grew naturally as the Mineral formed.
Nicholas Steno
The angle between two adjacent Crystal faces is identical to the angle of Crystal faces next to that angle. All angles Ina Quartz is 120 degrees. Pg 124
Crystal structure
The way in which atoms are packed
Anions
Atoms add elections and become negatively charged
Cations
Lose electrons to become positively charged
Halite
Rock salt- ironically bonded mineral, consists of oppositely charged ions that stick together Cuz opposites attract. Cl- and Na+.
Diamond
Made entirely of carbon. Atoms are in a tetrahedron. Covalent bonds are very strong in turn a diamond is very hard.
Graphite
Also made of all carbon it is opposite in look and hardness of a diamond. This is because of the shape the atoms are in they are in sheets and are bonded weakly in van see Waals bonds.
Polymorphs
Diamond and graphite.
Two different minerals have same compilation but have different Crystal structures
Five ways which a mineral can form:
- Solidification of a melt or freezing liquid.
- Can form by evaporation of liquid. Salt crystals
- Solid- state diffusion
- Bio Mineralization (fossils)
- Vapor. Pg 154
Geode
A mineral lined cavity in rock
Physical properties
Visual and material characteristics that distinguishes one mineral from another.
Most commonly used physical properties
Color, streak, luster, hardness, specific Gravity, Crystal habit
MOHs hardness scale
Helps in mineral identification. Helps compare hardness of a mineral with a common items. Such as fingernails and a penny
Silicates:
Silicon- oxygen tetrahedron. Most minerals in the earth crust. A silicon atom surrounded by four oxygens arranged Ina form of a tetrahedron. Examples: olivine and Quartz
95% of the continental crust.
Oxides
Consist of metal cations bonded to oxygen anions. Ex: magnetite and hematite
Sulfides
Metal cation bonded to a sulfide anion. Ex Helena and pyrite
Sulfates
Metal cation bonded to the SO2-4 a ionic group. Many font by perspiration out of water at or near the earths surface ex: gypsum
Halides
Anion in a halide is a halogen ion. Ex: halite and fluorite
Carbonates
CO 2-3 anionic group ex: calcite and dolomite
Native metals
Pure masses of a single metal. Metallic bonds. Copper and gold
Silicate - independent tetrahedra:
Independent and do not share oxygen atoms. Pg 161 ex: olivine and garnet
Silicate- single chain
Tetrahedra link to form a chain by sharing two oxygen atoms each.
Silicate double chains
Tetrahedra link to form double chain by sharing two or three oxygens. Black or dark brown elongate crystals with two cleavage directions
Sheet silicates
Tetrahedra in this group all share three oxygen atoms and therefore link to form two dimensional sheets. Ex: muscovite and biotite
Framework silicates
Each tetrahedron shares all four oxygen atoms with its neighbors forms 3-D structure. ex- feldspar and Quartz
Gemstone
Is a mineral that has special value because it is rare and people consider it beautiful.
Gem
Is cut and finished stone ready to be used in jewelry
