Prism of the first order Small 243×320 Medium 487×640 Large 779×1024 Download Tiff Original 1826×2400 | (436.7 KB) Description "This is a form consisting of six rectangular vertical faces each of which intersects two of the horizontal axes equally and the intermediate horizontal axis at one-half this distance." — Ford, 1912 Keywords first, geology, geometry, order, prism Galleries Prisms Source: William E. Ford Dana's Manual of Mineralogy (New York: John Wiley and Sons, Inc, 1912) 39
