GEOL-1021EL Lecture Notes - Lecture 4: Radiolaria, Calcite, Hematite
GEOL-1021
October 15th, 2017
October 19th, 2017
Earth Materials
What are Minerals?
ā¢Minerals are the building blocks of rocks
ā¢Naturally occurring
ā¢solid
ā¢crystalline substance
ā¢generally inorganic
ā¢speciļ¬c chemical composition (does not have to be ļ¬xed or pure within certain limits)
ā¢Exceptions to inorganic rule:
1. calcite: in shells/foraminifera
2. Silica in radiolaria
3. Apatite in teeth
ā¢Reason: these substances can also be produced by geological processes
ā¢Mineral or not?
ā¢Ice?
ā¢Hell yeah, itās a mineral. Fulļ¬lls all characteristics of the deļ¬nition.
ā¢Major component of the crust of both Jupiter and Saturn.
ā¢Has a distinct atomic arrangement
ā¢Coal?
ā¢No, bitch, itās a rock containing carbon in a variety of forms- some non-crystalline, as
well as other impurities. Elemental carbon forms two distinct minerals: graphite and
diamonds. Carbon is also a key component in a family of minerals: carbonates.
ā¢Amber?
ā¢Not a mineral. Non crystalline and only of organic origin.
How minerals form
ā¢Crystallization
ā¢Atoms come together from a solution in speciļ¬c proportions to form orderly
arrangements
ā¢the solution can be water based (precipitation due to cooling of heroes ļ¬uids/types of
sedimentary rocks)
ā¢Recrystillization
ā¢from pre existing minerals upon changes in temperature and pressure
ā¢increase
Main Mineral Groups
ā¢Silicates
ā¢Isolated silica tetrahedra
ā¢Single chain linkages (share two oxygens)
ā¢double chain linkages (three of two oxygens)
ā¢sheet linkages (share three Oxygens)
ā¢frameworks (share four oxygens)
ā¢Carbonates- calcite
ā¢oxides- hematite