Molding and Casting Fossils for Geology Laboratories

Abstract

The study of fossils in introductory geology serves as an important link between sedimentary rocks, geologic structures, plate tectonics, and geologic time. In addition, there is a strong public interest in fossils and paleontology. Unfortunately, fossil labs in introductory geology usually offer minimal, if any, coverage of major fossil groups. One factor contributing to this lack of coverage is the cost and availability of specimens.A reasonable solution is to produce molds of key fossils and to utilize casts for teaching collections. The use of casts is not a new concept, nor is the making of molds. However, directions for producing high-quality, reusable molds can be difficult to find. Latex, which is relatively inexpensive, has long been utilized as a molding agent; however, latex molds are easily distorted, do not reproduce fine details, and have poor durability. Although the initial investment required is high, vulcanized silicone-rubber molds will reproduce the finest of detail and are virtually indestructible. Literally thousands of casts can be produced from a single mold. If properly colored, fossil casts are nearly indistinguishable from original specimens.