Prehistorically, people of Alaska carved household tools from rocks, mostly slate. ‘Ulu’ is an Inuit word that translates as ‘woman’s tool’. It was used for household needs such as meat cutting. The Unangan civilization (Aleuts) in the late Aleutian phase (1000-200 BP) adopted the use of ulus sourced from slate, due to the rock’s durability and ease to sharpen. The paradox is, there is no slate widely present on the Aleutian Islands, yet fine grained volcanic rocks are abundant. In this study, I analyse 5 ulu fragment samples that were excavated on the Tanaxtaxak Spit (UNL_55), Amaknak Island of Unalaska where volcanic rocks and argillite were common. Kodiak Island, the nearest source of sufficient slate, is ~880 km away. The UNL_55 samples in this study were collected from different chrono-stratigraphic layers of the same site.The UNL_55 samples have previously been classified as slate, based solely on visual analysis. This implies possible inaccuracy in identification, since aphyric volcanic rocks and silicified argillite visually resemble slate. Using the Scanning Electron Microscope, I investigate the microtextures and minerals in the ulu fragments to identify whether they are slate, volcanic rock or argillite. Determining the rock type will guide inferences related to inter-island trade and migration of people in the prehistory of the Aleutian Islands. I expect the results to indicate rock composition that is similar to rocks that abundantly exist at the excavation site; volcanic.