Crystalline minerals such as fluorite have been recovered from numerous prehistoric sites in the Midcontinent yet little research had previously been conducted concerning who used it and what they used it for. Ethnohistorical accounts inform us that crystalline minerals were of importance to American Indians during the Historic Period. These accounts are used to provide a basis for exploring the possible significance of fluorite to prehistoric peoples living near outcrops located along the lower Ohio River valley. In this thesis I analyze mainly prehistoric fluorite personal adornment items as well as similar items made from other locally available raw materials such as cannel coal and clay to gain an understanding of the importance of this colorful crystalline mineral to prehistoric inhabitants of the midcontinent.