DREGS 2009 fall field trip convened Saturday afternoon, September 12 at the Shilo Inn in Casper, WY, as approximately 30 attendees gathered to learn about Evolving Gold Corporation's Rattlesnake Hills advanced-stage gold exploration project located ~75 km west of Casper. The field trip was a follow-up to the initial Rattlesnake Hills presentation made at the DREGS monthly meeting in May, 2009 by Evolving's senior geologist, Lew Kleinhans, and other Evolving exploration staff.
The Rattlesnake Hills (RSH) Project is an aggressive gold exploration program targeting bulk-tonnage style mineralization associated with Eocene alkalic intrusions, diatreme breccias, and volcanic rocks cutting Archean metamorphic basement rocks. Evolving's first-phase drill program during 2008 (15 core holes for ~6,500 meters) returned substantial gold-bearing intercepts involving both sub-1g/t and high-grade (>8g/t Au) mineralization over an area of 450x200 meters, and up to 550 meters depth. This success drew the attention of the metals exploration community and of gold investors alike, and by the time of the DREGS field trip Evolving was well-advanced in its 2009 drill program for >26,000 meters in >60 holes, with infill and step-out drilling being accomplished by five core rigs.

DREGS' field trip group traveled from the Denver area and outlying points and was welcomed by Evolving's staff Saturday afternoon at the hotel conference room. Lew then presented an informal summary of the project, in which he:

• Discussed the regional geologic setting of the NW-trending Laramide-age Rattlesnake anticline cut by NE-trending high-angle transverse fault corridors which appear to localize high-level Eocene alkalic intrusions;

• Reviewed history of gold exploration in the region, from discovery of gold anomalies by the Wyoming State Geological Survey in the early 1980s, to American Copper & Nickel's and Newmont's identification and drilling of gold targets in Archean banded-iron formations and Tertiary alkalic intrusions & volcanic breccias in the mid-1980 to mid-90s;

• Highlighted Evolving's exploration approach, its geologic observations & interpretations, and plans for the future.

Lew emphasized several encouraging geologic themes concerning the Rattlesnake Hills Project, including:

• Similarities of the RSH gold mineralization to other productive alkalic-related Cretaceous-Tertiary gold deposits along the Rocky Mountain foreland, such as Ortiz, NM, Cripple Creek, CO, and Zortman, MT;

• Multiple styles of gold mineralization at RSH, including bulk-tonnage style disseminated mineralization, higher grade gold in veinlets, stockworks and structurally-localized breccias, and possibilities for porphyry-hosted mineralization at depth;

• Variety of mineralized host rocks demonstrating the strength of the RSH system, and other geologic evidence suggesting that the mineralization encountered by Evolving may represent the upper part of a larger gold-mineralized hydrothermal system;

• Great location for an exploration project and mine (if warranted), with good access & infrastructure, and a welcoming political environment; and Exploration is still at an early stage, with many unanswered questions and much to be learned from drilling and ongoing technical investigations.

Following the presentation and question & answer session, attendees had an opportunity to view geologic maps and drill sections and examine representative rock and core samples from the project. Of particular interest were examples of carbonate-adularia-fluorite-sulfide (ÒAu) veinlets within more widespread potassic alteration by replacement adularia affecting the Tertiary volcanics & intrusions and the enclosing Archean schists; and the transitions from unmineralized to anomalous to ore-grade gold values within the overall alteration package. A variety of igneous, hydrothermal, and sedimentary breccias in drill core attests to the active tectonic setting of the RSH mineralizing system. Participants were on their own for dinner in Casper, and some reconvened later in the evening to continue examination of rock, drill core and maps.

Sunday morning we departed foggy Casper in a vehicle convoy, and soon emerged into antelope-dappled Wyoming grassland en route to the project site an hour away. Our first stop was a panoramic view of the Rattlesnake Hills anticline and project area, followed by examination of a roadcut exposure of poorly-consolidated Eocene heterolithic tuff deposited on Archean basement. A short distance away, we hammered on a paleo- phot spring terrace of travertine and bedded siliceous sinter developed proximal to a regional high-angle fault cutting Archean granite.

Our first stop within the RSH project was at the Antelope Basin target area, located ~700m south of the main gold discovery area at North Stock. Here we viewed a roadcut exposing a Tertiary-age pyritic quartz monzodiorite intrusion into shattered and iron-oxide stained Archean schist. Unlike the North Stock target, diatreme breccias are absent here, but both the quartz monzodiorite and some of the host schist are gold-mineralized. We then traversed downhill into exposures of brecciated quartz monzodiorite with carbonate, locally silica-cemented cave-fill (?) followed by a hike uphill through Archean meta-pelites cut by calcareous granitic injection dikes. From the hill above and immediately northwest of the Antelope Basin area, we had good views of drills working at thep porphyry-cored and diatreme breccia-mantled North Stock hill, and of prominent potassic alteration flanking the South Stock target area.

Our lunch stop featured sack lunches generously provided by Evolving Gold, and was accompanied by a Wyoming squall that sent everyone scrambling for rain gear. The storm passed quickly though (without snow, fortunately!), and the afternoon was spent on a variety of traverses that included outcrops of pyroclastic breccias and lahars; hydrothermal breccia dikes; examples of alkalic intrusions and their volcanic equivalents; and semi-gossanous exposures of Archean cherty ironstones that originally attracted ACNC to the gold potential of the region in the early 1980s.

Our final traverse presented the opportunity to search for fossil leaves & plant stems from Tertiary volcaniclastic sediments immediately below a resistant, hill-capping lithic tuff just southeast of South Stock. The afternoon concluded in cool sunshine as we returned to our vehicles from another successful DREGS field trip and set off for our destinations.

Many thanks to the DREGS trip organizers and individual drivers, and to Evolving Gold for allowing the informative project presentation and field visit. Special thanks go to Lew Kleinhans and his exploration crew for preparations, presentation, and logistical assistance in Casper and in the field. Updated drill results, maps, cross sections and photos for the Rattlesnake Hills Project can be viewed at www.evolvinggold.com .

Photos & Map

View north from Dry Creek Road toward Rattlesnake Hills.  Mesa in foreground is Miocene Split Rock Fm.; craggy outcrops beyond are Eocene alkalic porphyry of Evolving’s South Stock exploration target, intruded into Archean schists underlying the low hills between the mesa & South Stock.

View north toward North Stock target (conical hill at right traversed by drill road) from Antelope Basin Ridge.  Hill is cored by Eocene alkalic porphyry intrusion cutting Archean meta-pelites, and is mantled by diatreme breccia.  Rocks on both sides of the intrusive contact are gold-mineralized in subsurface.  Outcrops in right foreground are Archean schist.

Antelope Basin drill core: calcite+dolomite cemented monomict breccia of altered Archean schist, with crackle veinlets of fine-grained granular pyrite and minor crystalline adularia+pyrite filling vugs.

North Stock drill core:  Heterolithic diatreme breccia with coarse clasts of fine-grained Archean schist and juvenile magmatic clasts of Eocene alkalic porphyry.

Archean cherty ironstone at Rattlesnake Hills.

Evolving Gold’s geologic map of the Rattlesnake Hills Project area.

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DREGs field trip to the Cash Mine in September 2007, lead by Jim Paschis

Operations Summary of the Cash Mine, Mount Royal Ventures, LLC.
By Jim A. Paschis

Location The mine is in the central part of Sec.12, T1N, R72W, Gold Hill Mining District of Boulder County, Colorado, U.S.A. The town of Gold Hill lies in the western part of the section. Access is by way of County Road 52 (9145 Sunshine Canyon Drive), 9 miles west of Boulder at the Front Range foothills.

Cash Mine Headframe

Discovery history Placer gold was first discovered in the county in 1859 on Gold Run whose watershed includes the Cash Gulch. Gold-silver telluride veins were later discovered and staked in 1872. The lode discovery by B.N. Sanford is the Cash claim, M.S. #62, December 19, 1872. The mill site claim is the Cash No. 2 M.S. #544b by A. McClellan, September 10, 1872.

Mine development Access was by the Cash shaft following the steep northwest dipping vein to the 9th level. The head frame and hoist are in view on travel down to the current development at the 3rd level adit, 7,840 feet above msl. From that portal, 18-gauge track intersects the NNE striking Freiburg vein and extends through a cross-cut to the ENE striking Cash vein. On the Cash drift the secondary escape and ventilation raise collar are east of the Cash shaft. Currently, there are ten stopes in final development phase to provide 50 tons-per-day ore to the Gold Hill Mill near the mine property entry.

Geologic setting The intruding Boulder Creek Granodiorite, a 1.7 byr catazonal pluton, assimilated older Precambrian schist and gneiss in the area leaving only small xenoliths. This imparted a northeasterly biotite and feldspar phenocryst layering to the host rocks. This orientation is cross-cut by the 2nd order northwest trending, Laramide-reactivated Precambrian, Hoosier breccia reef structure, just west of the mine.

The mining district is one of several gold-silver telluride and tungsten districts on this part of the NE-SW trending Colorado Mineral Belt. This trend hosts a very wide variety of hydrothermal ore deposits and is coincident with a series of post-Laramide shallow intrusives along the Precambrian Idaho Springs Ralston shear zone. This shear is part of the 1st order, continental scale, Colorado lineament.

Geologic dating four miles south in the Boulder Falls-Sugar Loaf Mining District is 48 million years bp in a partially mineralized, latite porphyry dike cross cutting a ferberite vein. Tungsten and telluride mineralization is locally coeval and suggests that possible timing for ore at the Cash Mine telluride veins. Emplacement was possibly beneath at least 2,000 feet of pluton topped by the Eocene Flattop peneplain of the Colorado Front Range.

Mineralization Geologic site and mine mapping by Russ McClellan in the 1940’s provides further geologic insight to the many veins on the property. Very important to the property acquisition was the extremely detailed and verified gold and silver assay record provided by McClellan. This record guided stope development as late as the 1960s. Lower grade vein portions peripheral to those stopes are now undergoing re-evaluation and stope development by MRV. The ore-hosting veins are within shears and near aplites suggestive of re-activation of Precambrian structures. Pre-vein fault geometry controls the extent of ore deposition.

Gold is found as fine leaves, rarely as striated, curled horn, and as inclusions in the common silver telluride, hessite, on the 3rd level. The ore has a general ratio of Au : Ag = 1 : 6. Pyrite, galena, sphalerite and chalcopyrite with rare scheelite are associated with the tellurides. Fine-grained quartz, varying from clear to dark gray, locally known as “horn quartz” is the major gangue with subordinate carbonates and clays. Sulfidation of biotite left chlorite and pyrite flanking the veins.

Milling The mill makes a Knelson gravity gold concentrate and a froth flotation circuit produces a sulfide telluride concentrate. XRF analysis revealed that flotation beneficiation of 12 times was essentially identical with fire assay values. The concentrate is shipped off site for pyrometallurgical recovery of silver and gold.

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Brittle Structures, Kinematics, and Hydrothermal Alteration in the Central Colorado Rocky Mountain Front Range
A U.S. Geological Survey and Denver Region Exploration Geologists Society Field Trip, June 2, 2007
Jonathan Caine, (U.S. Geological Survey) and John Dreier (DREGS).

Use the above map to locate the location of the photos below.

Stop 1 - Clear Creek Quarry fault core, bordered
by “damage zone.”

Stop 2. Sheeted veins at left.

Stop 3. Blackhawk. “Slickenlines and shear sense indicators on this fault vein are an example of the many such structures that Bob Moench and others used to infer Laramide shortening directions associated with the formation of these mineral deposits. Caine took this one step further and used these data to model the paleostresses and show that permeability was controlled by the development of new fractures and the opening of preexisting fractures that were optimally oriented in the Laramide stress field. The model ENE shortening direction adds confirmation of the early work and new work along the eastern flank of the Front Range uplift,” (Caine, 2007).

Stop 4. Coal Creek Canyon. (Left) Laramide fault reactivation. (right) Clay-rich alteration at contact.

Stop 5. “Reef structures” (Magnolia Road)

Stop 6. Maxwell Reef

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Field Trip to SM-18 Mine September 23, 2005

Jim Pachis led a DREGS field trip to the SM-18 Mine September 23, 2005. A group of 13 were given an underground tour of Cotter's SM-18 Mine near Uravan. Geologists Dick White and Jane Zimmerman gave us a great tour of the mine.

The mine is located in southwest Colorado on the Colorado Plateau. It is found within the Uravan Mineral Belt, which resembles an arcuate lobe that extends from Polar Mesa in Utah, southeast into Colorado, and then bends to the south, and terminates along the southern boundary of San Miguel County (See Map). The SM-18 Mine is located at Uravan, in Montrose County, Colorado, along the San Miguel River.

History

The southern Utah - Colorado border area is known for uranium mainly in continental sandstones of the Salt Wash Member of the Upper Jurassic Morrison Formation. In 1898 uranium was first identified from the southwestern Colorado area but the deposits were sought primarily for their radium content. Early research was done be Pierre Curie and Marie Sklodowska Curie using radium concentrates from these ores for their work in France. Ores found later in the Congo (Shinklobwe Mine and others, about 1912) were characterized as being higher grade than Colorado ores, which caused the industry in Colorado to slacken. The recognition of the accompanying ferroalloy metal vanadium in the uranium ores led to a reopening of the mines. Tailings were located on a small island in the middle of the San Miguel River near the later town of Uravan after the metallurgical processing and recovery of vanadium.

Present day Uravan and the San Miguel River as seen from SM-18 (note the islands). © Doug Piper 2005

Note from Doug Piper: It is interesting to compare the above photo with my memories from a visit to Uravan in the late 60's. In the late 60's, Uravan was s small town covered everywhere with yellow dust - most memorable was the yellow dust. For more information on the history of Uravan including photos go to www.uravan.com/uravan.

In 1942 the intensely focused Manhattan Project sought uranium from all sources and the first available were the milled vanadium tailings - containing uranium. With the Hiroshima and Nagaski bombings ending WWII, the Cold War was on, and uranium prospecting and mining boom in the area regulated by the Atomic Energy Commission (AEC) continued until 1968. Uranium demand continued until the Three Mile Island and later Chernobyl incidents slowed nuclear plant development. Finally in the beginning years into this century, uranium prices bottomed out with the release of nuclear weapons stockpiles. With the consumption of these sources, present day prices are on the rebound to about 75% of the peak highs of 1980.

SM-18 Mine

This mine was acquired under the AEC lease program. It had originally been patented in 1926 for the contained vanadium as the Wright Mine. The ores mined are in the uppermost of three essentially flat-lying sandstone beds. The sandstones total about 300 feet thickness separated by mudstones.

The original uranium source is believed to be volcanic ash. The ash, erupted from volcanics to the north, was transported as airfall, and was deposited on continental sand and muds. Uranium, mobilized during the devtitrification of the glass, was by circulated by meteoric water and reduced by organic detritus.

The ratio of U:V at this mine is about 1:5. Farther south vanadium content increases the ratio to as high as 1:20. Uranium grades in the mine range from 0.2 to 0.25 per cent U3O8 and vanadium grades are approximately 1.3% V2O5. The mine has between 20,000 to 300,000 tons of reserves. Reserves in the mine are based on core drilling from the top side of Spring Creek Mesa (abbreviated as SM, and incorporated into the current mine name - SM-18). Several of these vertical core and rotary drill holes could be seen in the stope faces examined.

Primary minerals identified here are uraninite, pitchblende, and montroseite in addition to minor sulfides of galena, sphalerite, and chalcopyrite. Upon contact with moist mine air visible yellow carnotite, a secondary mineral, forms as a crust on the primary black mineralization. Locally grades are as high as 2 percent U3O8. Uranium appears to be localized by organic detritus which act as reductants to precipitate uraniferous minerals at short travel distance laterally, coincident with soft sediment dewatering prior to lithification. This is a rather different orogenesis than the hydrologic models developed for the oxidation - reduction interface mineralization concepts developed in the Wyoming sedimentary formation basins.

Yellow crust on the primary black mineralization. © Doug Piper 2005

Exploration

Cotter Corporation, which is now a General Atomics subsidiary, has drilled to as deep as 650 feet from surface in previous years. Ore delineation drilling was on 100-foot centers looking for thicker sands with reduced appearance. Most of the surface drilling was by rotory air. Drilling was followed up by truck mounted borehole gamma probes. Drill hole spacing at 100 -foot centers is not tight enough to fully delineate significant orebodies, and consequently ore horizons are followed underground along stratigraphic markers. Exploratory drifts are developed to further delineate the extent of subsurface mineralization.

Production

Cotter Corporation has a total of four producing mines in the Uravan Mineral Belt. In addition to the SM-18 Mine at Uravan, they have three underground mines to the south on the Monogram Mesa which are the JD-6, JD-8 and JD-9 Mines. The SM-18 Mine produces 150 tons/day and the remaining three active mines produce approximately 350 tons/day. The ores are trucked about 300 miles to the Canon City Mill for processing. Currently, Cotter Corporation is driving a 1,380-foot decline in the Slick Rock District on the south end of the Uravan Mineral Belt near Egnar. This mine, SR-11, may be in production in the later part of 2006.

DREGS Field Trip to the MolyCorp.'s Questa Mine, New Mexico

Jim Paschis led a group of 10 DREGS members on the 2006 DREGS field trip to Molycorp's Questa Mine. The field trip took place on Monday, February 26th. The Questa Mine, located in the Sangre de Cristo Mountains, is about 20 miles south of the Colorado - New Mexico border. It lies 5 miles east of the small town of Questa, and 6 miles west of the Ski Resort at Red River. The trip was a 4.5 hour drive from Denver, and the weather for our field trip was unseasonable warm, in the low 60s.

Molycorp was a subsidiary of Unocal until Chevron acquired Unocal last year. After the acquisition, Molycorp became a subsidiary of Pittsburg & Midway Coal Mining Co. (P&M) which is a subsidiary of Chevron.. Molycorp operates the Questa Mine and Mill in New Mexico, and owns the Mountain Pass Rare Earth Mine in California. Molycorp.'s Chief Geologist, Bruce Walker and its Senior Geologist, David Jacobs led the mine tour. In the morning Bruce and David gave an impressive presentation to our group. The material presented was instructive, and gave us an appreciation of the geology and mining, and environmental aspects at Questa. The afternoon was dedicated to a surface tour, which an overview of the surface geology, open pit mine workings, and important environmental features.

Here are a few photos from the field trip. A more detailed account of the field trip is forthcoming

Bruce Walker, Chief Geologist Molycorp's Questa mine (Allan Juhas in background) © Doug Piper 2006

Questa Mine Shaft #1. © Doug Piper 2006

Questa Mines' Glory Hole North Face © Doug Piper 2006

Another view of the glory Hole © Doug Piper 2006

Mosiac breccia with minor molybdenite © Jim Paschis 2006