Like many of the lessor mineralized areas in the San Juan Mountains, these prospects were first discovered and tested in the latter part of the 1800’s and in the early 1900’s. First recorded production is in 1913 and included some 57 tons of ore with 12 ounces of gold, 237 ounces of silver, 2,900 pounds of copper and 1,700 pounds of lead.

In the mid-1950’s, Mr. Reno Montonati, a local prospector interested in the silver in the area, discovered radioactivity at Tuckers Tunnel, did some development/exploration work and promoted the prospects for uranium. An engineer, he actually built his own helicopter and flew it in the area!

The collecting site, named the Tuckers Tunnel prospect, consists of a series of pits, trenches and short adits on an east-west trending structure cutting Paleozoic sedimentary carbonate-rich rocks. All minerals noted here have been found in the dumps at this prospect. The best mineralization was found in small openings in fractures and veins in blocks of angular carbonate-rich breccia with visible secondary copper mineralization. There are, however, many prospects, (the Mary Murphy Mine, for example) scattered in the area to the north that show copper mineralization and associated radioactivity. These prospects, unlike those at Tuckers Tunnel, do not show the variety of mineral species or the breccia that is the host for the minerals described here.

In the mid-1970’s I spent several field seasons working in the southern San Juan Mountains of Colorado.  One of the more interesting properties examined was in the Cave Basin Mining District located about 25 miles NE of Durango on the Hinsdale-LaPlata County common line. The area is reached from Forest Service gravel and dirt logging roads and a series of jeep trails starting at the NE end of Vallecito Lake. The primary collecting site, known as the Tucker’s Tunnel Prospect, is located on the north side of a prominent, rounded mountain known as Runlett Peak.

Access to this site may be limited. In 1976-77 this was a wilderness study area with an established wilderness about a mile to the north. Access on good gravel road from the north end of Vallicito Lake should take one to within about a mile of the prospect in any case. Elevations in the area range between 10,000 and 11,500 feet and there can be severe weather at any time of year.

This is a spectacular location for unusual micromount specimens.  Not only are there species first described here for Colorado (chonichalcite), but this is the type locality for a new mineral, theisite, first found here and described by contractors with the Bendix Corporation in 1982.

The best time for collecting at Crystal Hill is in the late fall through spring. In spite of the elevation, about 5,200 feet, temperatures are too high for most daytime work during the summer.

Camping at the site is permitted but there is no wood or water. Winter temperatures can be severe and access may be barred during periods of heavy snow on the passes to the north and south.

Note that the E-W fence that passes over the crest of the hill appears to separate public from private property. Do not trespass to the North.
The main collecting areas are well defined by the numerous pits and rubble piles left by diggers over the years. The dirt and talus on the slopes of the hill contain many crystals weathered from the upper outcrops that may be recovered by sifting the soil and small rocks. The numerous cavities and pockets along veins contain the best crystals but are hard to find and require a great deal of effort to excavate. Open cavities in the silicified rocks along the base of the upper outcrops under the crest of the hill illustrate the nature of the crystallization.

Tools needed include heavy bars, sledges and wedges with the usual assortment of smaller implements for working pockets. Be sure to bring a whisk broom and a small shovel for moving surface dirt from outcrops. And please, pack it out! This location is very clean with hardly a cigarette butt or gum wrapper noted. Let’s keep it that way.

The Crystal Hill quartz collecting location is in Inyo County near the small community of Deep Springs just west of State Route 168. It is some 25 miles east  from the community of Big Pine which is on Route 395 south of Bishop. The small farming community of Oasis is found about 11 miles to the north. The collecting site is clearly visible on the west side of the road as a relatively small hill with brownish color protruding east from the main mass of granitic rocks in the range of hills. It is about half a mile from the highway. Near the center of this bowl-like valley is a cattle guard with a gate and electric fence on the west. A dirt track follows the south side of the fence line about .3 miles to a fork where the access to the collecting area continues to the right following the fence another .3 miles to a parking area at the base of the hill.

Nearby collecting areas of interest are Crystal Ridge (quartz crystals) northeast of Independence and Gem Valley (amazonite, beryl, quartz) east of Lone Pine. Both are reasonably accessible and, as described, have great potential for an active collector. The writer has not yet visited either site.

Minerals of interest were found mostly in piles of mineralized sandstone blocks near the portals to the mine. This mineralized material has been exposed for years and soluble species have been dissolved and re-formed in cracks and on surface areas within the pile. You will need a typical assortment of tools that includes heavy sledges and bars to break up large blocks of sulphate-cemented sandstone. I recommend face masks and eye protection as dust from the pile is highly irritating and may contain radioactive species.

For a fairly complete list of minerals from the “Dexter Group” of claims see Bullock, Kenneth C., “Minerals and Mineral Localities of Utah” Utah Dept. of Natural Resources Bulletin 117, 1981. Of primary interest are sulphates that occur in micro to small thumbnail sizes such as coquimbite, roemerite, voltaite and others in association with alunogen, halotrichite, jarosite and a mix of massive, soluble, crystalline sulphates. Uranium minerals are present but were not seen as ‘collectible’ specimens.

For picture of some of these species see location references in the MINDAT database at www.mindat.org

The uranium workings at the south end of Calf Mesa in Emery County, Utah (the Dexter Group of claims)  have produced some of the more unusual and attractive sulphates known from the Western U.S.  Workings develop uranium mineralization in sandy units in the Chinle Formation of Triassic Age. While specimen production during actual development of the properties in the 1950’s thought to have been minor, abundant specimens were found as secondary accumulations in waste rock at the mines in the late 1980’s. There has been more recent collecting of specimens there but the extent of that activity is unknown. Because many of the minerals of interest at the Dexter Group are formed in waste rock and ores exposed to weathering there may be a continuing opportunity for collecting good specimens there for some time.

In the mid-1970’s I spent a good deal of time working on projects in Central and Southwestern Colorado. Among several areas of interest in the Gunnison area was an exploration project that incorporated much of the Italian Mountain intrusive complex, an area some 15 miles NE of Gunnison. This is one of the premier mineral collecting spots in the western US, one that has been recognized for the unusually fine specimens found there since it was first described by geologists in the 1870’s.

Later discovery of perhaps the only commercially significant North American deposit of gem-grade lazulite adds considerable interest. It is a place of sublime beauty that is seldom visited by mineral collectors because of it’s remoteness, elevation and lack of access for motorized vehicles.

Italian Mountain complex looking west from Italian Creek drainage

This writing will just introduce the reader to the area and the interesting geology and mineralogy there. There is a variety of literature available concerning the general area and the Italian Mountain complex itself. From the collectors point of view, the best reference is a fine article in The Mineralogical Record by Henry Truebe, (March-April, 1984).

Henry spent some time over a period of several years doing thesis work, mining specimens and evaluating the commercial potential for specimens in the area. He identifies and locates all of the significant species found there.

Italian Mountain is located between the Taylor River and Cement Creek drainages and is best approached from the east from a jeep trail that, starting just north of Taylor Reservoir, follows North Italian Creek to the area of the Star Mine in Star Basin. Several mines in this area produced small amounts of lead, zinc and silver from replacement ore bodies in limestone. The ponds in Star Basin are large enough to produce some fine trout for those interested in fishing. From Star Basin the trail turns south, rounding the east end of the long east-west trending ridge that separates Star Basin on the north from Stewart Basin to the south.

Stewart Basin with South Italian Mountain on left and Central Italian Mountain to right.
Vehicle is near the base of the trail that follows the east ridge to summit area.

American Flag Mountain forms a high North-South trending escarpment east of Stewart Basin. A foot trail from the south side of this ridge provides access from the ridge on the east flank of the main peak to the primary collecting area in a saddle at a contact zone just north of and below the 4,078 meter (13,380 foot) summit.

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Author on east ridge. Note colorful brown alteration of sedimentary rocks near summit and the lighter intrusive quartz monzonite porphry to the right.

Access from the head of Cement Creek follows a trail on the ridge northwest of the North Italian Mountain where the lazulite is found and skirts the peak of North Italian Mountain and approaches the summit of (Central) Italian mountain from the north across a talus slope. This is by far the most difficult access and the trail from the east is recommended. Note that the lazulite deposit is located on patented claims and is off limits to collecting without permission from the owners. Truebe located lazulite in several small occurrences around the main peak of Italian Mountain, but none proved to be of commercial interest.
The three peaks of the Italian Mountain intrusive complex are related to three intrusive ingneous stocks, the youngest of which is about 34 million years old and is usually described as a quartz-monzonite-porphyry (QMP). These rocks intrude Paleozoic sedimentary rocks that intrude limestones, dolomites, shales and quartzite. In these reactive rocks adjacent to the contacts with the QMP main stock and related intrusive dikes are developed skarn zones that contain the primary minerals of interest.

Steeply dipping beds of Leadville Limestone northeast of North Italian Mountain at the head of Cement Creek. The lazulite deposit is below and on a ridge to the left.

Italian Mountain summit from saddle to north. Note sedimentary beds and light-colored intrusive dikes and contact.

Looking north from peak to saddle collecting area. Note digging. Light-colored QMP talus and upper Cement Creek in background.

While there are some 80 mineral species described from the area, the most important and accessible to collectors are found in a relatively small area near the summit of Italian Mountain. These include vesuvianite (idocrase), garnet var. grossular, prenite, clinozoisite, epidote, diopside, chabazite and heulandite. Several pits have been opened on contact zones where these minerals have formed in skarns associated with intrusives and shaley sedimentary rocks of the Beldon formation. My favorite spot is in the saddle north of the main peak. Here the the west slope drops sharply some 500 meters to the Cement Creek valley and to the east is a near vertical drop of some 100 meters to a talus slope above Star Basin.

Ponds in Star Basin from saddle area north of main peak of Italian Mountain

In the 1970’s there were some remnant cables attached to the vertical cliffs below this area. Presumably they were used by some of Truebe’s crew to evaluate the contact zones on the cliff face. There are fine vesuvianite crystals here, up to 5-6 cm, although the best are those up to about 2.5 cm both on matrix and as floaters in collapsed pockets.

Vesuvianite, about 1cm, on grossularite-skarn matrix

Larger crystals, particularly those found near the east edge of the saddle area, tend to be corroded and may show unusual silky, fibrous vesuvianite surfaces. In addition, this is an area where there are gemmy grossularite crystals up to (rarely) 2cm.

Heulandite crystals to 3mm from saddle area.

A nice mineral collecting day trip from the Reno area is to the Nightingale Mining District, an area with many mines and interesting geology, flora and fauna. The area produced mostly tungsten with some by-products but has not been significantly active since the demand for the metal declined after the Korean War. There are a number of major mines with associated ruins as well as hundreds of smaller prospects. As with all such areas, approach any mining area with caution. Do not enter mine openings and remember that not all shafts and pits are fenced.

We approached Nightingale from the southwest from the south end of Pyramid Lake and the town of Nixon. Pyramid Lake is one of the largest and deepest desert lakes in the Great Basin; is is one of the remnants of the huge Lake Lahontan that covered thousands of square miles in northwestern Nevada several thousand years ago. From Nixon a gravel road trends north and east crossing a divide to the basin of Winnemucca (dry) Lake. This lake bed is long and narrow and parallels the Nightingale Mountains on the west. Our goal was the MGL mine, some 7 miles north of the main access road and a mile or two up into the mountains.

The road north passes some spectacular volcanic geology and excellent examples of ancient shorelines with associated tufa mounds. in several areas old beach deposits consist of hard, cemented gravels made up of black eroded igneous rocks that flank the basin in the area.

At the lower end of the canyon where the MGL Mine is located is the cement foundation of the processing plant where tungsten ores were concentrated. The ores were crushed and the heavier minerals containing tungsten were separated and concentrated during several stages of processing as they traveled down through the mill. Concentrates were hauled by truck to a railroad for transport to refining plants outside the area.

The road up the canyon required a bit of careful driving and would not be passable in wet weather. The ore chute or dump is located below the main mining operations. Open cuts in the tungsten bearing rocks can be seen above it. There are several adits (horizontal tunnels) that access the ore zones and allow the ores to be moved down and out to be loaded on trucks for the trip down-canyon to the mill.

The dumps around the ore chute and along the access roads contain many of the minerals that can be found in the open pits and tunnels. The MGL Mine is known for particularly fine specimens of large, brown andradite garnets as well as clinozoisite. Some of the best examples can be etched from calcite that fills some veins and pockets, protecting the crystals. Other minerals include pyrite, quartz, tremolite, copper secondary minerals and rare molybdenite.

Although the area is dry this time of year there are a variety of flowers and lots of lizards. Desert plume, Stanleya pinnata, is one of the more spectacular. Lizards like the black-collared, the western whiptail and the sagebrush lizard abound. It must have been a productive spring for them, because there were little lizards everywhere. It is amusing to see a 3-inch lizard on a 6-inch rock, protecting his territory with all of his bravado. The bigger lizards get to protect bigger rocks, and even graduate to a boulder if they are really assertive. And they run like the wind! Even the littlest ones will raise a small plume of dust as they dash down the road.

Returning to the main access road we again went northeast over a pass of about 6,000 feet in elevation to the site of the Nightingale Mines. Here are cement foundations and a metal stack and a large water tank that provided water for the milling operation. Most of the metal structures have been riddled by bullet holes and there is considerable trash left by campers. I have never thought of a water tank as a challenging target, but it must be.

The mining here was concentrated in a steeply-dipping sedimentary unit some 15 to 20 feet thick that has been metamorphosed by nearby and included granitic intrusives. The mining covers some half-mile of strike and has left large, open cuts and overhangs. Dumps contain a similar assortment of minerals as seen at the MGL Mine, but the rock is ‘tighter’ with less opportunity for good specimens where we checked.

Returning over Nightingale Pass we stopped at some smaller workings known as the Jay Bird Mine but found nothing of interest. The rest of the trip was uneventful. Pyramid Lake was calm and some the local white pelicans were having a meeting on the beach as we passed by. All in all a very good day.

This blog will be a site for sharing information about minerals, mineral collecting and related subjects for anyone with an interest. I look forward to hearing from others with news, collecting site information or those who just want to chat. I have personal experience in many areas including the midwest, west and some in the eastern U.S. but most current collecting is in Nevada and is somewhat limited to a few ‘old favorite’ sites.

I will be posting anecdotal information about some of the areas where I have had success or found things of interest over the years. I have a wide-ranging interest in things natural science, so if you are thinking of anything related, please send in a note.

Many thanks to Judith Harlan of harlaneditorial.com for her encouragement to start this blog. We are novices but expect to be ‘cruising right along’ in no time. Anyone thinking of starting a blog and looking for very professional help, please contact Judith. We’ve listed her link in our blogroll.

Steve Rose