Talla et al. (2013) posits that trace amounts of chromium do in fact play a role in determining the coloration of wulfenite. Here, the CrO42- anion group substitutes for the MoO42- group in the tetrahedral position. They found that as little as 0.002 atoms per formula unit () of Cr6+ substituting for Mo6+ is adequate to result in an orange-hued specimen. Cr6+ values of 0.01 were able to result in a red color. Talla et al. went on to emphasize that the colors result from a change of absorption intensity rather than a change of spectral position.