The type section for the formation is at Lone Mountain in T. 20 N., R. 51 E. Merriam (1940) restricted the Lone Mountain Formation to medium and light gray dolomites above the Roberts Mountains Formation.

The Lone Mountain is Silurian to earliest most Devonian in age (Berry, 1977) and is a western equivalent of the Laketown Dolomite. The Rabbit Hill and Windmill Limestones are partially equivalent to the upper portion of the Lone Mountain and the lower Beacon Peak Member of the Nevada Formation. The Lone Mountain is partially time equivalent to the Sevy Dolomite as well (Poole and others, 1967).

Winterer and Murphy (1960) and Berry and Murphy (1975) suggest the Lone Mountain interfingers with the Roberts Mountains Formation north and west of Lone Mountain, and that it is largely a regional lateral equivalent. The contact between the Lone Mountain and underlying Roberts Mountains Formation is gradational at Lone Mountain and in the Roberts Mountains and Hot Creek Range, but is sharp and lithologically diagnostic in the Diamond Range (Roberts and others, 1967; Kleinhampl and Ziony, 1985). In the Mahogany Hills the upper contact is considered a disconformity by Merriam (1960).

In the Hot Creek, Monitor, Fish Creek, and Sulphur Spring Ranges and the Diamond Mountains, the Lone Mountain consists of very light grey, massive, medium to coarse-grained, saccharoidal dolomite and dolomitic limestone which weather to a yellowish-orange (Merriam, 1963; Nolan and others, 1956; Larson and Riva, 1963; Kleinhampl and Ziony, 1985; Quinlivan and Rogers, 1974; Wise, 1977). Much of the dolomitization is a secondary post-depositional event which obscured original textures. Recrystallization has homogenized most bedding surfaces. Thick beds of alternating light and dark grey, coral-bearing dolomite are characteristic in the upper portion of the formation. Dark grey crinoidal dolomites are common near the base. Locally the unit contains coarse-grained dolomitic limestone near the lower contact, and dark-gray dolomite and thin quartz sands near the top of the formation (Kleinhampl and Ziony, 1985). The upper contact with the dark gray, well-bedded Nevada Formation is a gradational boundary that is quite distinctive in the field (Merriam, 1940). Scattered beds of quartz sand are particularly notable in the top of the section in the Hot Creek Range and at Lone Mountain, and may represent an unconformity on a regional scale (Quinlivan and Rogers, 1974; Kleinhampl and Ziony, 1985).

In the northern Reveille Range, the Lone Mountain Dolomite consists of an upper and lower sequence. The upper sequence is about 715 feet of color banded light to dark-gray, fine to medium-grained, thin to thick-bedded dolomite with finer grained dolomite and sandy quartzose dolomite near the top. The lower sequence is about 235 feet of fine to medium-grained, light-gray, massive dolomite with abundant secondary dolomite veinlets (Ekren, Rogers, and Dixon, 1973).

In the Carlin-Pinon Range, the Lone Mountain is partially exposed in several isolated exposures where it conformably underlies the Nevada Formation and overlies the Hanson Creek Formation (Smith and Ketner, 1975, 1978). The Lone Mountain was divided into three informal units with a lower member about 610 feet thick composed of brownish gray to yellowish gray, thinly laminated dolomite in beds about 2 feet thick, and a 10 foot thick sedimentary breccia zone near the top of the member. The middle unit is alternating brown and gray, finely crystalline, vuggy dolomite with small amounts of quartz silt. The upper unit is also alternating brown and gray dolomite in 2 to 3 foot thick beds which are vuggy, fetid, and fossiliferous (Smith and Ketner, 1978; Coats, 1985).

In the Ruby Mountains, the Lone Mountain is a medium to thick-bedded, sugary, massive and finely laminated, light to dark gray dolomite with locally abundant corals, crinoids, and brachiopods, and gray chert nodules (Sharp, 1942; Willden and Kistler, 1969). In the central Ruby Mountains, the Lone Mountain is divided into two members by an unconformity (Willden and Kistler, 1979), and rests unconformably on rocks ranging in age from Upper Cambrian to the Ordovician Ely Springs Dolomite. The lower member has a basal conglomerate with quartzite, limestone, and dolomite clasts overlain by 100 feet of platy, medium to fine-grained, porcellaneous dolomite, and 40 to 100 feet of medium to thick-bedded, medium-grained, dark gray to black, fossiliferous dolomite, and medium-to thick-bedded, sugary, light gray dolomite. A conglomerate composed of dolomite clasts is also present at the base of the upper member which is in turn overlain by cherty light-gray dolomite, about 200 feet of gray, fossiliferous and calcareous dolomite, and 700 to 1000 feet of light brown to gray thick-bedded to massive saccharoidal dolomite, interlayered with white to blue-gray sublithographic dolomite (Willden and Kistler, 1979; Coats, 1985).

To the south in the Buck Mountain-Bald Mountain area, Rigby (1960) called the Lone Mountain interval the Laketown and divided it into three units. The lower unit is about 30 feet of light to medium gray, sucrosic dolomite, overlain by a middle 230 foot thick band of dark gray-brown dolomite with minor interbedded light gray crystalline dolomite and an upper unit of 490 feet of poorly bedded, coarse-grained, light gray dolomite with thin dark gray dolomite interbeds (Rigby, 1960).

In the Spruce Mountain Quadrangle, although not mapped separately by Hope (1972), the Lone Mountain is included in a unit composed of light gray fine-grained dolomite which is strongly brecciated with the basal 200 feet containing small black chert nodules and Silurian pentamerid brachiopods (Coats, 1985).

Thicknesses of the Lone Mountain include 473 to 500 feet in the Hot Creek Canyon and Tybo areas of the Hot Creek Range (Lowell, 1957; Quinlivan and Rogers, 1974), 515 feet at Clear Creek in the Monitor Range (Wise, 1977), 950 feet in the northern Reveille Range (Ekren and others, 1973), 1,570 at Lone Mountain (Merriam, 1940), 2,190 feet in the Roberts Mountains (Merriam and Anderson, 1942), 3,200 feet in the Sulphur Spring Range (Roberts and others, 1967), 200 to 2,700 feet in the Ruby Mountains (Willden and Kistler, 1969, 1979; Sharp, 1942), about 750 feet near Bald Mountain (Rigby, 1960), 330 to 775 feet in the Carlin-Pinon Range, and about 1,000 feet in the Spruce Mountain Quadrangle (Hope, 1972).

The Lone Mountain Dolomite has been recognized within the Mahogany Hills, Antelope, Monitor, Fish Creek, Pancake, Hot Creek, and Reveille Ranges, Roberts Mountains, Lone Mountain, Sulphur Spring and Pinon Ranges, Diamond and Ruby Mountains, and the Spruce Mountain Quadrangle.

Matti and McKee (1977) have suggested the Lone Mountain represents skeletal or reefal carbonates that were originally mud and/or grain supported and were pervasively dolomitized and recrystallized during diagenesis. They suggest these dolomites represent deposition under shallow subtidal and peritidal platform margin conditions. This outer platform facies prograded westward over the laminated basinal limestones of the Roberts Mountains Formation.

Sugary saccharoidal dolomites in the formation represent secondary dolomite formed by diagenetic and minor hydrothermal recrystallization. Some of the finer grained dolomites in some locales are probably primary depositional dolomites (Nichols and Silberling, 1977).

Corals and brachiopods in the lower portion of the Lone Mountain are overlain with beds showing stromatolitic structures suggesting the environment of deposition shallowed upwards in the formation (Berry, 1977; McGoveney, 1977).

The Lone Mountain has moldic porosity development and has the potential for excellent local reservoir development.