CEE 1030 1st Edition Lecture 2 Outline of Current Lecture I Vocabulary Current Lecture Chapter THREE Minerals building bocks of Rocks Mineral by Geologists ordered internal structure specific chemical composition that may vary Naturally occurring inorganic solid Not the same as mineral supplements Rocks any loose solid made up of mineral Some can be made of non mineral matter ex non crystalline glassy volcanic Composition of minerals every sample of the same mineral has the same elements joined in a consistent repeating pattern Elements basic building blocks of minerals could have 2 or more elements in one Atom smallest unit of an element that still retains physical and chemical properties of that element Structure of an atom contains most of the mass of the atom Proton with a positive charge Neutron with no charge neutral Electron with negative charge cloud around nucleus Atomic number number of protons Mass number number of protons and electrons 12C 6p 6n Stable 14C 6p 8n Unstable Radioactive Decay ages Electronic structure of Atoms determines how atoms of elements fill out the structure and the electrons found in distinct energy shells Chemical Bonding stable configuration Ionic Bonding atoms gain lose outer most valence electrons to for ions Na cation 11p 10e Clanion 17p 18e Ionic Solid a chemical bond between two oppositely charged ions that is formed by the transfer of valence electrons from one atom to the other Covalent Bonding atoms sharing electrons Structure of Minerals consists of an ordered array of atoms chemically bonded to form a particular crystalline structure Cubic unit cell different crystals Polymorphs minerals with the same composition but different crystalline structures EX Diamonds and graphite Diagnostic Physical properties determined by observations or by simple tests Primary Characteristics Crystal Form external expression of minerals internal structure crystal growth often interrupted due to competition for space Luster way in which mineral surface reflects light Asbestos commercial term variety of silicate minerals that readily separate Color obvious feature but often unreliable as a diagnostic property of a particular mineral Gemstone names originate before mineral structure and composition were known Streak color of mineral in powdered form obtained on an unglazed porcelain plate Hardness resistance to abrasion or scratching Compared on a Mohs scale of hardness Use common objects Cleavage Fracture response of crystal to breaking Cleavage tendency of mineral to break along plane Produces flat shiny surfaces Secondary reaction to hydraulic acid Double fraction magnetism taste fluorescence smell elasticity Rock forming Minerals common minerals that make up most of the rocks of earth s crust The Silicates most important mineral group rock forming minerals Silicon Oxygen tetrahedron is the fundamental building block Dark Silicates ferromagnesian Mg Fe Light Silicates non ferromagnesian Ca Na K DEFINING A MINERAL NATURALLY OCCURRING GENERALLY INORGANIC SOLID SUBSTANCE ORDERLY CRYSTALLINE STRUCTURE DEFINITE CHEMICAL COMPOSITION THAT ALLOWS FOR SOME CARIATION Mineralogy The study of Minerals Periodic table An arrangement of the elements in which atomic number increases from the left to right and elements with similar properties appear in columns called families or groups Chemical compound most elements tend to join with atoms of other elements Octet rule A rule which states that atoms combine in order that each may have the electrons arrangement of a noble gas that is the other energy level contains eight neutrons Chemical bond transfer or sharing of electrons that allow each atom to attain a full valence shell of electrons Ion positively and negatively charged atoms Metallic bond A chemical bond that is present in all metals that may be characterized as an extreme type of electron sharing in which the electrons move freely from atom to atom Crystal Shape Habit refer to the common or characteristic shape of a crystal or aggregate of crystals Tenacity describes a mineral s toughness or its resistance to breaking or deforming Mohs Scale A series of 10 minerals used as a standard in determining hardness Density mass per unit volume Specific Gravity describes the density of minerals Crystal Crystalline any natural solid with an orderly repeating internal structure Unit Cell arrangement of basic building blocks cubic shape Steno s Law applies to all minerals because it holds for all minerals crystal shape is frequently a valuable tool in mineral identification Economic Mineral less abundant many other minerals are used extensively in the manufacture of products Silicate most common mineral group more that 800 silicate minerals are known and they account for more than 90 percent of Earth s crust Non silicate other mineral groups are far less abundant in Earth s crust than the silicates Silicon oxygen tetrahedron SiO4 4 covalently bonded to one comparatively small silicon ion forming a tetrahedron Polymerization achieved by the sharing of one two three or all four of the oxygen atoms with adjacent tetrahedra