The field of forensic geology can include all inorganic materials used as evidence, such as soil, building materials, and safe insulation. Generally, geologic material can be distinguished by the number of significant variations in the material. The usefulness of geologic materials is found, generally, in the ability to compare and contrast these variations. The article reviews the formation and composition of soil before moving on to discuss how building materials and safe insulation are used as geologic evidence. The Federal Bureau of Investigation (FBI) was one of the first law enforcement agencies to extensively use soil and mineral analysis in criminal cases in the United States. After describing the way in which soil is formed, either through a residual or transported process, the article turns to a discussion of the composition of soil. Soil is a complex system composed of solid, liquid, and gaseous materials. The definition of soil from a forensic perspective is “earth material collected accidentally or deliberately and associated with a matter under investigation.” The forensic value of soils lies in the fact that many variations and possibilities exist; including differences in composition, color, and structure. The article next turns to a discussion of the forensic use of building materials, which are defined as any natural materials that form manmade products that will become part of a structure. These materials can be distinctive because they are made of a combination of mineral or rock materials. Safe insulation, which is found between walls of fire-resistant and burglar-resistant safes, is soft and porous, making it easily transferable to clothing and tools. During an investigation, officers should take samples of all walls of a safe, keeping the sample dry and intact and free from cross-contamination. If appropriate procedures for collecting, storing, and preserving geologic materials, they can aid investigators in the determination of the facts of a criminal or civil case. 10 Endnotes