The Prospect Mountain Quartzite was named by Hague (1883) for exposures on Prospect Peak, the highest summit on Prospect Ridge, a northerly trending ridge which lies west and south of the town of Eureka. Unfortunately, the base of the unit is not exposed at the type section, and the entire section is positioned between two thrust faults making estimates of thickness imprecise (Nolan and others, 1956).

The Prospect Mountain Quartzite is lower Cambrian in age based upon its conformable contact with the overlying Pioche Shale. In the eastern portion of the evaluation area in the Snake and Schell Creek Ranges the base of the formation is placed at the top of the Osceola Argillite member of the Precambrian McCoy Creek Group and includes rocks mapped locally as the Stella Lake Quartzite (Hose and Blake, 1976).

No determinable fossils have been found within the quartzite. It is the oldest Cambrian formation over much of eastern Nevada, and locally includes rocks which are uppermost Precambrian in age. The Prospect Mountain Quartzite is time equivalent with the Gold Hill Formation in central Nevada and the Osgood Mountain Quartzite in the Northeastern portion of the state (Stewart, 1980; Kleinhampl and Ziony, 1985).

The Prospect Mountain Quartzite is the oldest exposed formation in the Eureka area where it is commonly highly fractured and poorly exposed as small angular talus blocks (Roberts and others, 1967). In the Eureka area, it is a white to gray, well-sorted, quartzite which weathers brown, pink or red, and often reveals faint cross-lamination along weathered surfaces. Micaceous and somewhat silty shale layers are more common in the lower portion of the formation and comprise less than 5 percent of the unit (Nolan and others, 1956). Thin conglomeratic beds are present in some exposures.

A small 700 foot long and 250 foot wide fault bounded block of Prospect Mountain Quartzite was described on a ridge between Hancock Canyon and Mill Creek in the northern Shoshone Range (Gilluly and Gates, 1965). This exposure is the westernmost outcrop of the Prospect Mountain in the evaluation area. It is composed of highly sheared, fine-grained, white to brown weathering quartzite which shows faint cross-bedding. Slivers of sheared and silicified shale, sandstone and sandy shale a few feet in thickness, are present between the quartzite and the overlying Roberts Mountains Formation, and may represent the Pioche Shale (Gilluly and Gates, 1965).

In White Pine and northern Nye Counties, the Prospect Mountain Quartzite is quite uniform lithologically, and sections exposed in the Egan and Cherry Creek (Fritz, 1960, 1968; Woodward, 1962, 1963), Grant (Hyde and Huttrer, 1970; Cebull, 1967), Quinn Canyon (Kleinhampl and Ziony, 1985) Schell Creek (Young, 1960; Misch and Hazzard, 1962; Drewes, 1967), and Snake Ranges (Misch and Hazzard, 1962; Drewes and Palmer, 1957) are described in composite below.

The Prospect Mountain in these ranges consists mainly of pinkish gray to light olive gray, brown to yellowish gray weathering, massive, fine to medium grained quartzite in beds from 6 inches to 8 feet thick. The quartzites commonly consist of about 80 to 95 percent quartz, with 5 to 15 percent feldspar with minor amounts of muscovite. Well developed cross-bedding is often accentuated by color banding, and thin pebbly lenses are also present within the quartzite (Dechert, 1967). Interbedded greenish to purplish shaly and silty quartzites and argillites, commonly a few feet and up to 100 feet in thickness, are common in most sections (Young, 1960; Misch and Hazzard, 1962; Hyde and Huttrer, 1970; Hose and Blake, 1976). The base of these argillitic beds occasionally shows ripple marks and sole markings of various types (Misch and Hazzard, 1962). Possible worm borings are present in the section in the southern Egan Range (Kellogg, 1960).

In the Highland and Bristol Ranges, the Prospect Mountain Quartzite is described as a thin-bedded to massive, reddish-brown quartzite which alternates with thin-bedded quartzite, and interbedded micaceous green shale, with white to pinkish massive quartzite forming the upper several hundred to 1,000 feet of the formation (Tschanz and Pampeyan, 1970). Diabase dikes cut the unit near Pioche and in the Delemar mining district.

In Elko County, the Prospect Mountain is exposed in several ranges. In the Ruby Mountains, the Prospect Mountain is a brown and gray weathering, foliated and cross-bedded, medium to coarse-grained metaquartzite with approximately 80 to 90 percent quartz, 10 to 20 percent feldspar, muscovite and biotite and local magnetite and sillimanite (Sharp, 1942; Smith and Howard, 1977; Willden and Kistler, 1979). The basal portion of the unit is coarse-grained and poorly sorted arkosic quartzite and micaceous pebble conglomerate up to a few tens of feet thick.

In the Jarbidge Mountains, the Prospect Mountain Quartzite makes up most of Copper Mountain Ridge (Coats, 1964, 1985) as a thick, white, massive quartzite with thin beds of mica schist and a basal cobble conglomerate sharply overlying the Precambrian McCoy Creek Group. In the Bull Run Mountains, the white to red-brown, fine to medium grained orthoquartzite is conspicuously cross-bedded, and includes thin quartz-pebble conglomerate and schist interbeds (Decker, 1962; Clarke and others, 1985).

In the Rowland Quadrangle, the unit is composed of a lower portion of thin to thick-bedded, light gray quartzite with schistose interbeds, and laminated thin-bedded dark quartzite. The upper portion is poorly sorted, well-rounded quartzite interbedded with chloritic schists (Bushnell, 1967).

In the Pilot Range, the Prospect Mountain is a white to light gray or pink, red to red-brown weathering, massive and low-angle cross-bedded quartzite which is fine to medium-grained and highly jointed and fractured (Blue, 1960).

In the northern Toana Range, the Prospect Mountain is a medium to coarse-grained, well sorted, micaceous quartzite with planar and festoon cross-bedding (Pilger, 1972). In the northern Schell Creek Range, the Prospect Mountain is light rose to white, fine to medium-grained, cross-bedded quartzite which contains a few thick layers of green or purplish phyllitic shale and purplish quartzite (Young, 1960). In the southern Deep Creek Range, the unit is massive and well-bedded, cross-bedded, pinkish, white and brown quartzite with lenses of sub-angular to rounded quartzite conglomerate (Nelson, 1959).

The Prospect Mountain has undergone low-grade metamorphism, particularly along detachment faults in the Snake, Schell Creek, and Toana Ranges where some of the argillaceous interbeds are somewhat phyllitic, and the quartzites and shales have been recrystallized to rodded quartzites and garnet-staurolite schists (Hose and Blake, 1976; Misch and Hazzard, 1962; Pilger, 1972).

The Prospect Mountain Quartzite varies in thickness from about 300 feet in a small fault bounded section in the northern Shoshone Range (Gilluly and Gates, 1965), to 1,500-1,660 feet at the type section, about 20 feet are exposed in the White Pine Mountains (Lumsden, 1964), 4,000 to 5,000 feet in the Snake Range (Whitebread, 1969), about 4,500 feet in the central Schell Creek Range (Kellogg, 1960; Hose and Blake, 1976), 2,200 to 2,730 feet in the northern Schell Creek Range (Young, 1960; Dechert, 1967), 4,500 feet in the central Grant Range along Grant Canyon and about 3,000 feet near Troy (Hyde and Huttrer, 1970), 3,700 to 4,200 feet in the Bull Run Mountains (Decker, 1962; Clark and others, 1985), over 2,500 feet in the southern Deep Creek Range (Nelson, 1959), 1,500 feet in the Jarbidge Quadrangle (Coats, 1964), and 3,500 feet in the Rowland Quadrangle (Coats, 1985).

The Prospect Mountain Quartzite is often incompletely exposed in the northern Shoshone Range, Eureka area, Ruby Mountains, Egan, Grant, Quinn Canyon, White Pine, Toana, Pilot, Schell Creek, Cherry Creek, Snake, southern Deep Creek, Bristol, and Highland Ranges, Bull Run and Jarbidge Mountains, and Rowland, Mount Velma, and Marys River Basin Quadrangles.

The Prospect Mountain Quartzite represents shallow marine nearshore strandline deposition as indicated by trace fossils and herringbone, planar and festoon cross-stratification, ripple marks, mud cracks, worm burrows, algae, and archeocyathids.

Clark and others (1985) have suggested that the thickly bedded and cross-stratified sandstones of the Prospect Mountain Quartzite represent a fluvial system which migrated over a deep Precambrian lacustrine rift basin in the Bull Run Mountains.