Introduction In the first week's lab, class members had to classify six unknown rocks into one of three rock types: igneous, sedimentary, and metamorphic. We would then have to use that knowledge, along with other characteristics of the rocks, to determine the name of the rock. This document will identify each of the six samples based on observations of each sample in the laboratory. The article will continue by discussing the main properties of igneous, sedimentary and metamorphic rocks. This article will conclude with a discussion of which classification of a rock is the most useful in determining its name. Rock A - Marble Rock sample A is marble. “Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism” (King, 2013). This particular sample is white in color and contains medium and coarse grains. The grains are visible and are easy to feel when I pick up the rock and move it in my hands. Marble has many uses in architecture and sculpture, making it a popular material for these applications. Rock B - Gneiss Rock B sample is gneiss. This sample was easy to identify based on the obvious bands present in the sample layers. Gneiss is another metamorphic rock that was originally an igneous rock, granite. Through the process of metamorphism, the heat and pressures associated with the process may have caused the layers of mineral grains to flatten. “Gneiss shows distinct alternating layers composed of different minerals. Gneiss does not break along foliation planes because less than 50% of the minerals formed during metamorphism are aligned in thin layers” (UA, 2005). A visual inspection of the rock shows the composition of quartz and feldspar within the layers of the sample. Rock C - Limestone Rock C sample is limestone. Limestone is “organic sedimentary rock that forms from accumulation