Trigonal Prism Small 320×279 Medium 640×558 Large 1024×892 Download Tiff Original 2400×2091 | (337.1 KB) Description Principal forms of the hexagonal system: trigonal prism Keywords forms, geology, hexagonal, trigonal prism Galleries Prisms Source: Amadeus W. Grabau A Textbook of Geology (Boston: D.C. Heath & Co., 1920) 46 Courtesy the private collection of Roy Winkelman
