Named for exposures on west side of Hartmann Gulch, just north of Ophir, T5S, R4W, Tooele Co, UT in the Great Basin province. No type locality designated. Also crops out on north wall of Ophir Canyon. Overlies Lower and Middle Cambrian Ophir formation; boundary is transitional; upper contact of Ophir placed at top of highest shale bed. Conformably underlies Middle Cambrian Bowman limestone (new); the basal bed of the Bowman is a prominent ledge. Ledge is resistant to erosion because of its being metamorphosed from limy shale to hornfels. Consists dominantly of limestone banded with mudstone. Some of the bands are parallel to the bedding. The weathered surfaces of the limestone are irregularly mottled light-gray, buff, and brown. Section 654 ft thick measured on spur above Wild Delirium mine where the limestone is dark blue gray (fresh) and light gray (weathered). Some of the limestone beds in the measured section are cross bedded; some are poorly bedded, oolitic. Some buff to cream-weathering sandstone layers. Lower part is equivalent to the lower part of the Teutonic limestone of the Tintic district. Few fossils found. Assigned to the Middle Cambrian. Geologic section, stratigraphic table.

Source: GNU records (USGS DDS-6; Denver GNULEX).