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And some rin uphill and down dale, Knapping the chucky stones to pieces wi’ hammers, Like sae mony roadmakers run daft – They say it is to see how the warld was made. - Sir Walter Raleigh Minerals Webpage for course (daytime) Webpage for course (nighttime) Lecture 4 Something from the ancient Greek philosopher-scientists What is a mineral? A naturally occurring inorganic solid made up of an ordered arrangement of ATOMS Difference between minerals and rocks Atoms, three basic parts Mass (wt.) Protons Neutrons Electrons charge nucleus electron cloud Fig. 2.5 Atomic number = Atomic mass number = Atomic number = number of protons Atomic mass number = number protons and neutrons Example: Carbon (symbol “C”) atomic number = atomic mass number = Therefore, 6 protons, 6 (12-6) neutrons Periodic Table A balanced atom has as many electrons as protons Electrons are not randomly located Occur in “shells” electrons fill shells in a sequential order 1st shell holds up to 2 electrons 2nd shell holds up to 8 electrons 3rd shell holds up to 8 electrons Two rules in Nature: 1. electrons occupy shells in a specific order (inner before outer shells) 2. Outer shell that has electrons in it must be full of electrons Two rules in Nature: 1. electrons occupy shells in a specific order (inner before outer shells) 2. Outer shell that has electrons in it must be full of electrons Let us develop some characters Our cast of characters Our cast of characters element Hydrogen sym + H Helium He Carbon C Oxygen O Sodium Na Chlorine Cl Iron Uranium Fe U +/- - # wt. outer sh. Needs So let us meet a hydrogen atom after the Big Bang… When Harry met Sodium Sally Chlorine More formulae CaCO3 (calcite) KAl2(Si3Al)O10(OH)2 (muscovite) Ca3Al2Si3O12 (garnet) Silicate minerals SiO4 tetrahedra Isolated Olivine Chains Hornblend Sheets Mica Framework Feldspar & Quartz So, what the atoms are and how to go together determines the characteristics of the mineral: crystal shape hardness cleavage chemical properties etc. etc. Graphite and Diamond
