Lithium (Li) is one of the fundamental metals used in modern and future technologies. Even with how critical it is in modern society, demand for Li will only increase in the coming years. Lithium is used primarily in batteries, and as such is a key component for, e.g., electric vehicles. Most lithium is extracted from salars and Li-pegmatites. However, the behavior of Li in terms of its mobilization, transportation, and deposition are still poorly understood. Even the analyses of Li is challenging. This presentation will break this into three aspects; how is Lithium analyzed, what are Earth's Li geochemical signatures, and how does one get this range of fractionation. In this presentation, we will discuss diverse tested methods and their pros and cons, as well as the analytical hurdles faced and overcome in the field of Li geoscience. We discuss the diverse ranges of Li isotopes measured throughout the Earth's crust, with a particular focus on the ranges relevant to Lithium deposits. Finally, we will discuss the fractionation factors leading to the observed isotopic ranges, with emphasis made on the environmental effects that affect a given sample from deposition to erosion. Overall, Li is a complex system, and our goal is to show the methods with which one can investigate Li, the questions we ask, and what some of the answers are.