Lab 1 Minerals I Definition of a Mineral Mineral 1 Naturally occurring 2 Solid 3 Formed by geological processes 4 Inorganic 5 Definable chemical composition 6 Crystalline structure II Physical Properties of Minerals Luster the appearance of a fresh mineral surface in reflected light 1 Metallic luster looks like metal 2 Non metallic luster doesn t look like metal 3 Vitreous non metallic luster looks like glass 4 Earthy non metallic luster not bright like glass Mohs Relative Hardness Scale to tell if gypsum scratch with fingernail if it scratches than gypsum not calcite Cleavage tendency of a mineral to break along planes of weakness if it breaks due to stress and broken piece retains a smooth plane or crystal shape NO CLEAVAGE never produces any crystalized fragments fracture occurs when there are no zones of particularly weak bonding irregular or conchoidal curved surfaces form quartz III Know which of the minerals are SILICATE minerals 1 Olivine Isolated independent structure light green color 2 Pyroxene Single chain structure two planes of cleavage that intersect at 90 3 Amphibole Double chain structure 4 Mica Biotite and Muscovite Sheet Structure one directional plane 5 Plagioclase and Orthosclase Feldspar non metallic luster 6 Quartz Framework Structure 7 Talc 8 Kaolinite the one that looked like chalk and came off on our hands IV Other Mineral Groups 1 Oxides Hematite there were two samples in lab leaves a red brown streak on the streak plate rust color rust oxidation 2 Sulfides Pyrite fools gold metallic luster sphalerite yellow brown shiny leaves no mark or streak 3 Sulfates gypsum can scratch with your fingernail 4 Native Elements gold and diamond possibly graphite im not sure 5 Halides If you are desperate scratch it and see if it tastes like salt halite three mutually perpendicualer planes of cleavage fluorite 6 Carbonates calcite will fizz with HCl acid three planes of cleavage one is incline rhombus shaped V Other minerals from lab that have not been described already Galena metallic black leaves black streak mark Graphite greasey feeling shiny black writes like a pencil on paper magnetite only one that attracted a magnet Lab 2 Igneous Rocks I Definition rock naturally occurring solid aggregate of minerals or of organic material igneous rock origin from cooling and subsequent crystallization of magma Named based on texture and composition of rock II Texture and Composition of Igneous Rocks A Texture 1 Phaneritic coarse grained with fine B Composition minerals are macroscopic in size can see individual minerals 2 Aphanitic fine grained minerals are microscopic in size cant see individual minerals 3 Porphyritic mixed texture in which macroscopic crystals are embedded in a matrix of microscopic crystals looks like big chunck of minerals grained material around them 4 Porous vesicular rock with holes usually spherical to rubular in shape 5 Glassy looks like glass shine and very smooth obsidian 1 Mafic basaltic contain lots of Mg Ca and Fe minerals usually dark colored olivine pyroxene plagioclase feldspar magmas composed of 50 silica lower amounts of K Na and dissolved gases 2 Felsic Silicic 65 77 silica higher amounts of K Na and dissolved gases lower amounts of Mg Ca and Fe minerals usually lighter colored both feldspars both micas quartz 3 Intermediate have both mafic and felsic components III Identify Rocks based on texture and composition 1 Granite phaneritic felsic 2 Diorite phaneritic intermediate 3 Andesite apanitic intermediate 4 Gabbro phaneritic mafic 5 Basalt aphanitic mafic 6 Rhyolite Porphyry porphyritic microscopic crystals are felsic 7 Basalt Porphyry porphyritic microscopic crystals are mafic 8 Peridotite Ultramafic in composition contains mostly olivine green tint 9 Obsidian glassy in texture 10 Pumice vesicular texture vesicles are small extremely light weight 11 Scoria vesicular texture vesicles are large and numerous red color IV Know four minerals that are in Granite quartz orthoclase potassic feldspar muscovite and biotite mica lesser amounts of amphibole and plagioclase feldspar V Know four minerals in gabbro plagioclase feldspar pyroxene olivine lesser amounts of amphibole VI Know which rocjs had slow fast or mixed cooling aphanitic texture magma cooled rapidly crystals did not have time to grow phaneritic texture magma has cooled slowly allowing larger crystals to grow porphyritic texture magma has cooled slowly then rapidly allowing for both micro and macro scopic crystals to grow vesicular testure gases have excaped from the magma as it flowed to the surface glassy texture magma cooled extremely rapidly gases were not present at the time Lab 3 Sedimentary and Metamorphic Rocks I Definition of a Sedimentary rock origin is from 1 erosion transportation deposition and subsequent lithification of pre existing rocks near or at the surface of the earth 2 from organic biochemical or inorganic chemical reactions 3 from lithified accumulations of organic debris if origin is from 1 clastic or detrital sedimentary tocks 2 chemical sedimentary rocks 3 organic sedimentary rocks like coal II Textures of a Sedimentary Rocks 1 clastic aggregate of mineral grains rock particles or fragments of organic remains clastic sedimentary rocks include conglomerate beccia sandstone siltstone and shale 2 crystalline composed of interlocking crystals only two crystalline ones in lab chert and micrite micrite was smaller one chert is harder than micrite and will scratch it III Composition of Sedimentary Rocks 1 Carbonate mainly calcite or dolomite 2 Siliceous mainly quartz grains or crecipitate of silica 3 Evaporites formed by chemical precipitation when saltwater evaporate gypsum halite 4 Organics contain remnants of organic chemicals and may be more than 90 C 5 Argillaceous rocks contain mostly clay shale IV Identify Sedimentary Rocks 1 Conglomerate clastic texture with large rounded rock fragments 2 Breccia clastic texture with larer angular rock fragments 3 Sandstone clastic texture with sand sized particles 4 Siltstone clastic texture with silt sized particles 5 Shale clastice texture with clay sized particles not visible to naked eye argillaceous 6 Limestone crystalline or clastic texture containing calcite with carbonate composition reacts to hydrochloric acid Fossiliferous Limestone containes fossils one that had shell imprints in it Crystalline Limestone crystalline texture Coquina clastic texture with calcite material oatmeal looking one 7 Chert Crystaline