Lab 7 - Sedimentary Rocks

4) Organic. These are layered accumulations of organic material formed where algae or plants (NOT mineral matter) get buried before it they be completely decomposed or recycled back into the living biosphere. Since classifying organic compounds is beyond the scope of this course, we will examine only one kind of organic sedimentary rock – coal. Coal can form different “grades” depending on how concentrated carbon is in the preserved organic matter and how much thermal energy is per unit volume when it is burned. There are other organic sedimentary rocks like oil shale and tar sand. These are relatively uncommon and we’ll pass on those. Together coal, oil shale and tar sand are what we call “fossil fuels.” Follow this link and lookup the different “ranks” of coal and list them in order from lowest grade to highest grade: Within each category: clastic, chemical, biochemical and organic rocks are identified on the basis of different textures and mineral compositions. From the list below, choose which terms refer to a rock’s texture (T), and which refer to a rock’s composition (C): Banded Fossiliferous Sand Calcareous Gravel Silt Clay Hematitic Well-sorted Coarsely crystalline Limonitic Rounded Cryptocrystalline Micaceous Angular Feldspar-rich Poorly-sorted Finely crystalline Quartz-rich From the list below, indicate which genetic category each rock type belongs to: D for Detrital C for Chemical B for Biochemical O for organic Bituminous Coal Crystalline Dolostone Micaceous siltstone Calcareous shale Fossiliferous dolostone Fossiliferous limestone Chalk Graywacke Rock Salt Chert Quartz sandstone Shale Conglomerate Limonitic breccia Travertine