Exposures of Jasperoid Breccia have been retained by several workers as a map unit where large exposures are present, such as those in White Pine County where a total of 4 square miles of jasperoid outcrops were mapped (Hose and Blake, 1976). The term is applied to very dense and hard, siliceous and ferriginous rock most commonly derived from Paleozoic limestones such as the Joana and Ely. It is often a light to very dark gray or red in color, locally shows liesegang banding, and may or may not show brecciation with elongate and angular clasts of the surrounding country rock.

Much of the jasperoid is clearly related to faults such as in the Ruby Mountains, Cherry Creek, and Egan Ranges. Often these jasperoids are spatially related to intrusives that are also spatially associated with surrounding faulting. The breccia itself is often arsenic, cobalt, copper, zinc, and locally gold bearing as a result of replacement of the host by the silicifing hydrothermal fluids. The limonitic selvages around most of the jasperoids actually carry most of the gold values. Perhaps the easiest way to find jasperoid breccia in the field is to look for claim posts, either made of wood or unmistakable white PVC pipe. The jasperoid is often used quite successfully as an ore deposit indicator. Hose and Blake (1976) suggest much of the jasperization is probably Pliocene in age, at least in the Egan Range and Ruby Mountains. Small exposures of jasperoid are present in Elko County within the Owyhee Quadrangle, and in a brecciated mass of Joana Limestone to the east of the northern end of the Dolly Varden Mountains (Coats, 1985).