The Rook project is a Carlin-style sediment-hosted exploration property in the southern portion of the Battle Mountain-Eureka Trend and at the east edge of the Northern Nevada Rift. The property consists of 87 unpatented mining claims 100% owned by Miranda.
Exploration completed during 2010 identified a prospective region about 2.5 mi (4 km) long and 1 mi (1.7 km) wide with elevated Carlin-style pathfinder elements (Au, Ag, As, Sb, Hg) and alteration along the cross-faulted Roberts Mountain Thrust (RMT). Silicified rocks in the vicinity of the mapped edge of the RMT yield rock chips with up to 505 ppb Au (0.015 oz Au/t).
The Rook claim block encompasses 2.6 sq mi (6.7 sq km) in the northern part of the Roberts Mountains of Eureka County, Nevada, and is about 33 mi (53 km) northwest of the town of Eureka (Fig. 1). Access is by approximately nine miles (14.5 km) of gravel and dirt roads generally southwest from state highway No. 278 starting 38.5 mi (62 km) north-northwest of Eureka. The area is in moderate to steep terrain with elevations ranging from 6,200 to 7,200 feet (1,890 to 2,195 m). Dominant vegetation is juniper and pinion pine trees (Fig. 2).
The geologic setting of the Rook project is similar to other Nevada major sediment-hosted gold deposits in its localization of alteration and mineralization by high-angle faults cutting favorable gold-host stratigraphic units in both the lower and upper plates of the regionally extensive Roberts Mountains Thrust (RMT). Figure 3 shows the geology of the Rook project area. Erosion through the RMT exposes the lower-plate Devonian carbonate sequence of (older to younger) the McColley Canyon Formation, lower and upper members of the Denay Limestone, and Devils Gate Limestone. Units in the upper-plate of the RMT are separated by low-angle imbricate faults parallel to bedding such that the stratigraphic sequence is generally reversed. From the bottom upward they are (generally younger to older) the Mississippian Webb Formation; two unnamed Devonian units of limestone and shale, and shale and chert; Vinini Formation, Upper Ordovician Upper Member chert and shale; unnamed Devonian unit of chert and argillite; and Vinini Formation, Middle Ordovician Lower Member sandstones. Miocene basalt dikes, components of the eastern edge of the north-northwest-trending Northern Nevada Rift, intrude the lower plate carbonates and the Webb Formation.
The project area is complexly faulted. All stratigraphic units, the RMT, and the low-angle faults separating upper-plate units generally dip east. From west to east the exposed stratigraphic sequence (lower plate---RMT---upper plate) is thrice repeated by generally north-trending sequence-bounding normal faults with down-to-the-west displacement. The sequence-bounding faults both terminate and are cut by east-northeast- and northeast-trending faults which are cut by Miocene basalt dikes.
Alteration (Fig. 3) and surface geochemistry on the Rook property are consistent with leakage from Carlin-style sediment-hosted gold deposits. The eastern-most sequence of lower plate---RMT---upper plate extends 2.5 mi (4 km) north-northeasterly across the claim block and for its entire length the Devils Gate Limestone footwall and portions of the Webb Formation hanging wall to the RMT are silicified. Less extensive zones of silicification occupy the same stratigraphic position in the central and western sequences. Additionally, a patch of silicification centered on the western sequence-bounding fault is 1,000 ft (300 m) across and alters rock on both sides of the fault.
Rock chip geochemical samples (Fig. 4) from the Rook property are anomalously high in the pathfinder elements (Au, Ag, As, Sb, Hg) characteristic of Carlin-style sediment-hosted gold deposits. Miranda rock samples (111 samples), mostly from silicified zones across the property, range up to 505 ppb Au (0.015 oz Au/t), 18.5 ppm Ag (0.54 oz Ag/t), 3,340 ppm As, 728 ppm Sb, and 105.5 ppm Hg.
A shaft and head frame at the site of the old Lead Bar mine (Fig. 2) and a few shallow prospects and trenches give evidence of early prospecting and mining in the Rook project area. Miranda has no production data on these workings.
Modern exploration in the Roberts Mountains has been conducted by Asarco, Atlas, Barrick, BHP, Columbus Gold, Great American Minerals, Hemlo Gold, Newmont, Platte River Gold, and Miranda. ASARCO outlined the small Chert Cliff gold resource at the Devils Gate Limestone---Webb Formation contact 4,000 ft (1,200 m) south-southwest of the Rook property. Numerous dirt roads in the Rook project area attest to previous drilling of which Miranda has no records.
In 2010 and 2011 Miranda conducted reconnaissance mapping and rock chip sampling (111 samples).
The Rook project is in the Battle Mountain-Eureka gold trend. The property contains the Webb, Devils Gate, Denay, and McColley Canyon formations in outcrop, and all these units host ore in various gold deposits on the Carlin or Battle Mountain-Eureka gold trends. Exploration targets at Rook occur where these units are cut by faults along which the rocks are altered and mineralized with pathfinder elements (Au, Ag, As, Sb, Hg). The Webb---Devils Gate contact, especially, is extensively silicified and geochemically anomalous. Altered and geochemically anomalous zones in areas with multiple fault intersections may represent regions of particularly focused hydrothermal fluid flow and significant mineralization. Potentially mineralized stratigraphic horizons are within drillable depths. The Webb and Devils Gate units on the property are about 460 ft (140 m) and 600 ft (180 m) thick, respectively. Drill holes collared in the Webb Formation and at least 1,200 ft (365 m) deep should be able to test potential mineralization at the Webb---Devils Gate contact as well as in the upper part of the Denay Limestone. Holes collared in the Devils Gate or Denay formations could intersect the McColley Canyon Formation.
Miranda's Business Model
In accordance with Miranda's business model, a joint venture partner will be sought to further explore the Rook project.