GEOL 1001 Lecture : Geology Notes September 16th
Document Summary
A rock is made of 2 or more minerals which can be the same or different. Ex: granite contains plagioclase feldspar, biotite, quartz, and orthoclase feldspar. Ex 2: a rock completely made of quartz, or a rock made of sand (sandstone) Solid - naturally made -inorganic -ordered internal structure specific chemical composition. All metamorphous and especially igneous rocks are crystalline, sedimentary are more likely to be clastic. Look at the size of the grains/minerals/crystals, shape of minerals (rounded/ angular), layering of minerals (overall composition) Crystal form shape that crystals can grow into which is controlled by a chemical formula and how the atoms arrange themselves. Cleavage/ no cleavage (the way a mineral breaks) breaking on cleavage plane also known as plane of weakness, breaking in a specific area and or shape, controlled by the bonding of atoms. When a rock has no cleavage, it will fracture. Color streak (powdered minerals and the color of powder determines classification)
