Summary:
There are three styles of gold occurrences identified on the Property, including: 1) intrusive-hosted sulfide disseminations and sulfide-quartz stockwork veinlets (such as the Dolphin gold deposit); 2) auriferous sulfide-quartz veins; and 3) shear-hosted gold-bearing veinlets. All three types are considered to be part of a large-scale intrusive-related gold system on the Property.
Instrusive-Hosted Sulfide-Quartz Veinlets
Intrusive-hosted, auriferous sulfide disseminations and auriferous sulfide-quartz veinlets (0.1-5 mm) within the Dolphin stock are spatially associated with the highest gold grades within the Dolphin gold deposit. Gold also occurs with disseminated euhedral arsenopyrite (1 to 5 mm) which appear to be an earlier, higher temperature mineralization event (McCoy and Olson, 1997). Gold mineralization within the deposit also occurs as mineralized fault gouge enriched with sulfides, sulfide-rich veins, and locally as narrow sulfide-quartz veins <6 inches thick; however, these comprise a relatively small portion of the total gold resource.
Gold within the Dolphin gold deposit occurs largely as inclusions in sulfides, and locally as visible grains, within the sulfide-quartz veinlets. Pyrite and arsenopyrite is the most common sulfide mineral, although stibnite, lead-antimony sulfosalt minerals, tetrahedrite, scheelite, galena and sphalerite occur locally. McCoy and Olson (1997) identified two distinct varieties of arsenopyrite in the Dolphin gold deposit based on arsenopyrite geothermometry and age relations. McCoy also noted that older “hotter” arsenopyrites were finer-grained compared to younger “cooler” arsenopyrites, which were generally coarse and bladey. Furthermore, the high-temperature arsenopyrite contains particulate inclusions of gold, whereas the low-temperature arsenopyrite contains maldonite (a gold-bismuth mineral). Although stibnite and antimony sulfosalts are not uncommon in the deposit, geochemical studies suggest that high antimony values are generally associated with very low gold values. Evidence suggests that the fluids evolved towards increasing base metals and antimony with time. For example, chalcopyrite embayments in pyrite were noted in thin section, and massive sulfide veins (jamesonite, galena, stibnite and/or sphalerite) cutting arsenopyrite-quartz veins are noted in several drill logs. In addition to sulfides, some portions of the Dolphin gold deposit contain abundant scheelite.
Auriferous Quartz Veins
High grade auriferous quartz veins (2 cm to 3 m), hosted in metamorphic rocks, occur at numerous locations, and were the source of all previous gold production from the Property. A discussion of each occurrence is beyond the scope of this report; the general mineralogy, morphology and structural setting is summarized below. Detailed information for individual vein prospects on the Property can be obtained from previous reports (Freeman, 1992).
The auriferous quartz veins typically crosscut the host rock primary foliation at very high angles. A large number of these veins dip south, although some veins dip north. Vein thickness is quite variable, and can range from a few inches to several feet over short distances along both strike and dip. Pinch-and-swell features, bifurcations and splays are characteristic.
Auriferous quartz veins on the Property consist of hydrothermal quartz with minor to trace amounts of sulfides. The veins are opaque to milky white quartz and locally gray to mottled gray and white. Bands or laminations parallel to the vein walls are not uncommon, and vein centers often contain vuggy or comby quartz crystals. Silicified vein breccia is also common, and may comprise the entire vein or be restricted to bands within the banding sequence (Adams and Giroux, 2012). This suggests there were most likely multiple, possibly alternating episodes of silicification and deformation. Auriferous quartz veins seldom contain more than 5% total sulfides and average 1- 3%. The most common sulfide is arsenopyrite, although other sulfides are locally present, including pyrite, stibnite, jamesonite, tetrahedrite, galena and sphalerite. Scheelite is present in a few specific veins (notably abundant in the Cleary Hill and Wyoming vein). Visible gold typically occurs as coarse flakes, filigree, or wires suspended in quartz or mingled with sparse, scattered sulfides. Locally the auriferous quartz veins may be accompanied by parallel stringers and pods of later massive stibnite. This massive stibnite occurs locally as <10 inch (<0.25 m) thick seams or pods parallel or adjacent to auriferous quartz veins, and also as veins up to 4 feet (1.3 m) thick along steep cross-faults which offset the auriferous quartz veins. This stibnit mineralization is thought to be formed as the last metal-bearing event at lower temperatures.
Shear-Hosted Veinlet Zones
Shear-hosted auriferous veinlet zones on the Golden Summit Property are found within some of the same shear zones which host major auriferous quartz veins and, as mentioned above, are likely parts of the same mineralization event. The key characteristic of these zones is that they may contain sufficient polyphase veinlet density and gold grade to justify bulk-mining methods. Several of these zones have been explored since about 1969, including the Too Much Gold prospect, the Circle Trail and Saddle prospects, and the Curry Zone.
The shear-hosted veinlets consist largely of quartz with variable amounts of sulfides, although locally the veinlets may consist largely of sulfides with lessor amounts of quartz. Sulfide-quartz veins within the shear-hosted zones generally are less than a few centimeters in thickness. Locally these veins form vein sets with spacing of a few feet, resembling a sheeted vein system (vein swarm). The veins are discontinuous along strike and dip, and often grade into broken veins, vein breccia, or zones of sugary, granulated crush quartz material. Higher quartz vein and veinlet density is generally indicative of higher gold values.
The shear-hosted veinlet zones are characterized by pervasive sericite and clay alteration, as well as localized silicification and carbonate alteration. In addition, the zones are typically highly oxidized near the surface, and contain locally intense iron, arsenic or antimony oxides. The majority of the veinlets within the zones are sub-parallel to the strike and dip of the zone.