Ocher as a prospecting medium in the Montezuma district of central Colorado

Ocher occurs widely In the Montezuma district as small sinters and as bedded deposits of bog iron and ocher-cemented conglomerates. The iron of the ochers is derived from pyrite-rich veins and from pyritic hydrothermally altered rocks. Trace amounts of ore metals in the ocher and its admixed detritus are partly from the pyritic source rocks but also include contributions from other rocks and ores in the watershed, both during and after formation of the ocher deposit. Ocher is evidence for the presence and character of the generally ill exposed pyritic rocks, which are important, in evaluating the porphyry-metal system of ore deposits. The trace-element composition of the ocher is at best a qualitative guide to the ore metals present in the provenance of the ocher deposit but not to their abundance or necessarily to their mode of occurrence.