 Some species are used as dyes . H. caeruleum , used in North America and Scandinavia to dye silk and wool , produces a range of colors including tan , blue , and forest @-@ green , depending on the mordant that is used . H. peckii produces gray , brown , and olive colors . Hydnuferrugin and hydnuferruginin are pigments responsible for the coloration of H. ferrugineum and H. zonatum . Geogenin is a yellow pigment found in H. geogenium . 
