A Grimelius stain will generally stain the chromaffin granules dark brown to black. However it is a rather variable stain, which depends a fair bit on the skills of the histotechnologist. You may have more reproducible results with a immunohistochemical approach, for instance staining for chromogranin A or synaptophisin, both of which should pick up chromaffin cells.
Immunoperoxidase stains for chromogranin, synaptophysin or CD56 will stain the enterochromaffin cells. Histochemical Grimelius for argyrophil and Masson Fontana for argentaffin granules on histologic techniques that are quite tricky.
Didn't you ask similar question at: https://www.researchgate.net/post/plz_suggest_any_stain_which_differentiate_adrenal_gland_part_and_also_chromaffin_cell_except_H_and_E
NB just to inform 2017-May-12: an action by Manisha gladly was encountered at https://www.researchgate.net/post/plz_suggest_any_stain_which_differentiate_adrenal_gland_part_and_also_chromaffin_cell_except_H_and_E .