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Minerals - Part II. 7 Major mineral groups. Nature’s most common building block in rock forming minerals is the … Silica Tetrahedra SiO 4. 1) Silicate Minerals. Quartz is the second most abundant mineral on the earth’s crust
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7 Major mineral groups • Nature’s most common building block in rock forming minerals is the … • Silica Tetrahedra SiO4
1) Silicate Minerals Quartz is the second most abundant mineral on the earth’s crust (the most abundant element on the earth’s crust is therefore oxygen)
Feldspars • Feldspar is the most abundant “family” of minerals on the earth’s crust. The various feldspar minerals make up over 60 percent of the crust. • (Aluminum ions replace silicon ions)
Feldspars • Feldspar is used for ceramics (china) and glass
Micas • Micas are soft silicates found in many rocks - micas most distinctive feature is that it has one cleavage surface – they are pearly and ‘flake’ easily
Micas • Micas are used for electronic insulation
Amphiboles • – complex type in the silica group where iron and magnesium have replaced a silica ion.
Carbonates Carbonate mineral group is made up of compounds of one carbon and 3 oxygen atoms (CO3) joined with various metal ions
Carbonates react with acid (HCl); calcite reacts strongly with acid, other carbonate minerals react only mildly with acid.
Other Carbonate Minerals • Dolomite = CaMg(CO3)2 • Siderite = FeCO3
Oxides Metal + oxygen = oxide • For example: Hematite = Fe2O3 Franklinite = (Zn,Mn,Fe)2+ (Fe,Mn)3+2O4
Sulfides Metal + sulfur = sulfide • For Example: Pyrite = FeS2
Sulfates Sulfur + 4 Oxygen atoms = Sulfate SO4 • For example: Barite = BaSO4
Halites (Salts) Compounds of elements and chlorine, fluorine, iodine or bromine For example: table salt = NaCl, potassium salt = KCl
Native Elements • Elements found uncombined with other elements, For example: gold silver copper sulfur diamond
7 Mineral Groups (in relative order of abundance) • Silicates – minerals that contain silicon & oxygen, and usually one more element • Carbonates – contains carbon w/3 oxygen atoms • Sulfates – contains sulfur w/four oxygen atoms • Halides – compounds of certain elements and chlorine, fluorine, iodine or bromine • Oxides – compounds of elements and oxygen (usually rust looking) • Sulfides – compounds of elements and sulfur • Native Elements – elements found uncombined w/other elements (copper, gold, etc…)
Look familiar? Felspar… Microcline Distinguishing feature: the ‘laminae’ – little veins in the mineral
Garnet Ca3Al2(SiO4)3
Look familiar? • Hornblende: • striated appearance • hexagonal cross-section • Dark-dark green to black
Look familiar? • Magnetite • magnetic
Look familiar? • Olivine • Light to dark green • Really hard (6.5-7)
Look familiar? • Franklinite • Stubby metallic crystals, usually in calcite
Look familiar? • Zincite • red • vitreous • orange-yellow streak • Willmenite • green • strongly fluorescent green