CRD / Combined Metals limestone
Pioche CM bed Zn-Pb-Ag-Mn-Au
Metals on this play: zn, pb, ag, mn, au
Calibration
Prince Mine, Caselton / Combined Metals No. 1, Pan American — Pioche, Lincoln County, NV. USGS PP 171.
The trap
Host. Combined Metals limestone (and equivalent replacement beds) in the Pioche / Highland section.
Trap. Carbonate replacement along fissure feeders. Godbe mill, aerial tram, Caselton mill, Prince Mine lineage.
What a hit looks like. Jasperoid, Mn-oxide, gossan on limestone. High Zn+Pb on XRF. This is Caselton, not a sandstone reef.
Wrong mountain
Do not XRF a limestone CRD with a sandstone-Ag checklist. Do not mix Combined Metals (Paul Gemmill / Caselton) with Tungsten Comet (David Lewis).
- Host is sandstone with wood — Plays A–D.
- Host is Prospect Mountain quartzite vein — Play F.
- Wolframite vein — Play G (Comet), not the CM bed.
- Gulch gravel / placer nugget — Play H. The 24-lb story is Osceola, not Caselton.
- Lake Mead wad / tuffaceous Mn (Three Kids, Boulder City deposit) — Play J, not Combined Metals limestone.
- Epithermal quartz-calcite in Eldorado volcanics — Play I.
How to use the score
The score orders the day. It is a walk sort. It is not an assay, a mining claim, or permission to enter. Killed ground stays on the map so the boundary is visible. Private land, tribal land, and park interiors stay off the walk.