Collecting Tourmaline at the Himalaya Mine, California

Tourmaline - 5.7cm - photograph from Rob Lavinsky, iRocks.com

The Himalaya Mine is a location that rock and mineral collectors dream of: rich mineralization featuring gem minerals in stunning color!  The extraordinary minerals that come from this mine have made it world famous – lucky for you, the mine offers a pay dig site where you can keep all you find!

Before we get to the pictures of pretty minerals, let’s talk a little about the history of the Himalaya Mine!  (If you really can’t handle this part, you could scroll past, but you’d be missing out on some cool stuff!)  The Himalaya Mine was officially located in 1898, though early reports indicate that local Indigenous Peoples knew of the gem crystals.  Legend has it that white settlers located the mine after noticing Indigenous children playing with tourmaline crystals!

Gail Lewis was the original claim holder on the mine, though only held the property for four years.  In 1902, J.L. Tannenbaum, an employee of Tiffany & Company and a very controversial man, acquired the property through claim jumping.  Keep in mind, this is the original usage of the term “claim jumping,” meaning Tannenbaum filed another claim over the top of Lewis’ existing claim.  Much legal to-do ensued over this, but Tannenbaum retained the property.  The mine was then operated by Tannenbaum with J. Goodman Braye as mine superintendent.  Braye is a very interesting figure in mining history, as his position as superintendent was one of significant power and respect and he also happened to be an African American in the early 1900s.

First workings on the Himalaya Mine

Original caption: “First workings on the Himalaya mine at Mesa Grande, which was later to become one of the greatest tourmaline producers in the world. Left to right: Heighway, who filed on the Himalaya for Tannenbaum of New York; Vance Angel (center above) who was foreman 1900 – 1912; J. Goodman Bray, Jr., colored protege of Tannenbaum who was in charge of the Himalaya; Lohrer, first foreman of the mine; La Chapa, Indian worker. Photo courtesy Vance Angel, Mesa Grande.”  Reprinted from the bimonthly magazine Calico Print, Vol. IX, No. 4, July 1953, 40pp. The Calico Press, Twentynine Palms, California.

In the following ten years, reports indicate that 6 tons of tourmaline were shipped for use as lapidary material out of an estimated production of 110 tons produced by the Himalaya Mine and neighboring mines.  This would equal value at the time of more than $750,000!  By 1904, the surface workings were mined out and work had moved underground.

One of the principal demands for tourmaline was overseas in the Chinese market, where pink and red gemstones were highly prized by the Dowager Empress.  This drove a highly speculative market until the overthrow of the Chinese aristocracy in 1911.  The downfall of the Chinese aristocracy caused the tourmaline market to crash and ended the early production period at the Himalaya Mine.

Pink Tourmaline snuff bottles – 19th century – Qing Dynasty – photograph from Christie’s Auction House.

Sporadic small scale mining operations continued between 1913 and the early 1950s.  In 1957, Ralph Potter began another attempt at systematic mining at the Himalaya, including rehabilitating several older underground workings and driving several new tunnels.  Potter operated the mine for several years, but a collapse of the main tunnel in the winter of 1968-1969 ended underground mining.

In 1977, Bill Larson of Pala Properties International leased the property, later purchasing it in 1988.  This period saw extensive tunneling and underground expansion, and produced a relatively consistent stream of minerals in comparison to earlier projects.

The Himalaya Mine is now operated by High Desert Gems & Minerals, who also facilitate the pay dig site.

Over its life, the Himalaya Mine has produced an estimated 250 thousand pounds of tourmaline and mineral specimens.  In its most active 15 years, it produced more tourmaline than any other tourmaline mine in the world, including 5.5 tons in 1904 alone (the most tourmaline ever produced in a year).

For more on the history of the Himalaya Mine, see:

Fisher, J., Foord, E. E. and Bricker, G. A. (1999), The geology, mineralogy, and history of the Himalaya mine, Mesa Grande, San Diego County, California. California Geology 52(1): 3-18.

Jacobson, Mark Ivan (September 2010): Lippman Tannenbaum: President of the Himalaya Mining Co. and a Difficult Person, Mineral News, Vol. 26, No. 9.

Jacobson, Mark Ivan (January 2017): The Early History of the Himalaya Pegmatite Mine – San Diego County, California, Mineral News, Vol. 33, No. 1.


So, what you really want to know: what can you find?!

Tourmaline – Elbaite:

Tourmaline, Lepidolite, and Quartz - 14 cm across - photograph from Rob Lavinsky, iRocks.com

Tourmaline, Lepidolite, and Quartz – 14 cm across – photograph from Rob Lavinsky, iRocks.com.

The Himalaya Mine’s most notable mineral is tourmaline, a complex hexagonal boron-aluminum-silicate mineral group.  Most tourmaline from the Himalaya Mine is the species elbaite.  The tourmalines can range in color from black to vivid pink to apple green, and some crystals even feature multiple colors!  Blue tourmaline is also present, but is rarely found.

Approximately 5% of tourmaline from the Himalaya Mine are gemmy, meaning they have the high translucency that allows them to be faceted into glassy gem stones.

Elbaite - a gemmy crystal showing greens and pinks - 3.9cm tall - photograph from Rob Lavinsky, iRocks.com

Elbaite – a gemmy crystal showing greens and pinks – 3.9cm tall – photograph from Rob Lavinsky, iRocks.com.


Lepidolite:

Lepidolite on Hambergite - 4.5cm tall - photograph from Rob Lavinsky, iRocks.com

Lepidolite on Hambergite – 4.5cm tall – photograph from Rob Lavinsky, iRocks.com.

Lepidolite is a series of the mica group minerals.  Lepidolite is rich in lithium, though the pink to red color of lepidolite is usually attributed to manganese content.  Because lepidolite is a mica group mineral, it is often very flaky, but some material can be used in lapidary work.


Quartz:

Quartz on Microcline - 7.8cm - photograph from Rob Lavinsky, iRocks.com

Quartz on Microcline – 7.8cm – photograph from Rob Lavinsky, iRocks.com.

Since the Himalaya Mine is a pegmatite mine, quartz is common throughout the deposit.  It can occur as clear “rock crystal” quartz, milky quartz, and even smoky quartz.  Some top specimens feature tourmaline or other minerals attached to quartz in beautiful ‘combination’ specimens.

Elbaite on Quartz - 6.0 cm - photograph from Rob Lavinsky, iRocks.com

Elbaite on Quartz – 6.0 cm – photograph from Rob Lavinsky, iRocks.com.


Microcline:

Microcline (Carlsbad twin) - 6.0 cm - photograph from Rob Lavinsky, iRocks.com

Microcline (Carlsbad twin) – 6.0 cm – photograph from Rob Lavinsky, iRocks.com.

Like quartz, feldspar is an integral part of the mineralogy of the Himalaya Mine.  The most common feldspar species found is microcline.  Microcline from the Himalaya Mine is often beige to colorless, and can featured etched surfaces as well as crystallographic twinning.  Microcline is rarely gemmy from anywhere in the world, and this is also true at the Himalaya: it will likely appear as blocky opaque white-ish crystals.

Etched Microcline (twinned) with Albite and Lepidolite - 10.1 cm - photograph from Rob Lavinsky, iRocks.com

Etched Microcline (twinned) with Albite and Lepidolite – 10.1 cm – photograph from Rob Lavinsky, iRocks.com.


Albite – variety Cleavelandite:

Albite on Orthoclase with Tourmaline – 8.6cm – photograph from Rob Lavinsky, iRocks.com.

Albite is another of the feldspar species present at the Himalaya Mine.  It often occurs as the variety Cleavelandite, which occurs as thin, platy crystals.  Cleavelandite at the Himalaya Mine often occurs in beautiful rosettes of colorless to very faint blue, and can often be somewhat translucent.

Albite on Microcline with Quartz and Lepidolite - 25.0 cm - photograph from Rob Lavinsky, iRocks.com

Albite on Microcline with Quartz and Lepidolite – 25.0 cm – photograph from Rob Lavinsky, iRocks.com.


Fluorapatite:

Apatite - 2.3cm - photograph from Rob Lavinsky, iRocks.com

Apatite – 2.3cm – photograph from Rob Lavinsky, iRocks.com.

Fluorapatite from the Himalaya Mine is a uncommon, but is worth looking for!  Colors range from colorless to blue to intense pink.  Fluorapatite from the Himalaya Mine is light sensitive, so be prepared for colorless crystals on the surface and be sure to protect any colored crystals you happen to find.

Apatite on Quartz - 4.1cm - photograph from Rob Lavinsky, iRocks.com

Apatite on Quartz – 4.1cm – photograph from Rob Lavinsky, iRocks.com.


Beryl, topaz:

Beryl (etched) - 2.9cm - photograph from Rob Lavinsky, iRocks.com

Beryl (etched) – 2.9cm – photograph from Rob Lavinsky, iRocks.com.

While beryl and topaz do occur at the Himalaya Mine, they are exceedingly rare.  Keep an eye out for oddities though – you could get lucky!  Beryl can occur as etched “floater” crystals, though fully formed crystals have also been found.  Beryl colors at the Himalaya include goshenite (colorless), morganite (pink), and aquamarine (blue).  Topaz is so rare at the Himalaya that we couldn’t even find a photo to share with you!  Both beryl and topaz will likely look much like quartz, though there are physical qualities to help distinguish them – be sure to make use of the staff at the mine to help answer questions you have about your finds!

Beryl (morganite) - 11.7 cm - photograph from Rob Lavinsky

Beryl (morganite) – 11.7 cm – photograph from Rob Lavinsky, iRocks.com.


Hambergite:

Hambergite - 4.4cm - photograph from Rob Lavinsky, iRocks.com

Hambergite – 4.4cm – photograph from Rob Lavinsky, iRocks.com.

Hambergite is another relatively rare pegmatite mineral that often occurs with beryl.  Well-formed crystals of hambergite are hard to come by from anywhere in the world, but they can be found at the Himalaya Mine.  They occur as creamy white crystals, but can also range from an orange-ish tint to a salmon orange-pink.  They are sometimes opaque and sometimes gemmy, sometimes etched and sometimes sharp.  Again, if you have questions about what you are finding, ask the staff – they’ve seen a lot of this material and have a lot of knowledge to share!

Hambergite – 2.9cm – photograph from Rob Lavinsky, iRocks.com.


Stilbite:

Stilbite-Ca - 5.5cm - photograph from Rob Lavinsky, iRocks.com

Stilbite-Ca – 5.5cm – photograph from Rob Lavinsky, iRocks.com.

Stilbite occurs at the Himalaya Mine as white to cream colored crystals often found in “wheat sheaf” shaped sprays of crystals.  Stilbite is technically a super group of zeolite  (framework alumosilicate) mineral species, but that chemistry makes it even more interesting at this locality!  Stilbite rarely makes stand-alone specimens at the Himalaya (though that’s still possible!) – but look for it in combination with other minerals!

Stilbite on Tourmaline - 2.8 cm - photograph from Rob Lavinsky, iRocks.com

Stilbite on Tourmaline – 2.8 cm – photograph from Rob Lavinsky, iRocks.com.


Stibiotantalite, Columbite-(Mn), and other “ugly” minerals:

Stibiotantalite (zoned) - 1.8cm - photograph from Rob Lavinsky, iRocks.com

Stibiotantalite (zoned) – 1.8cm – photograph from Rob Lavinsky, iRocks.com.

For those of you who also love the “ugly” minerals of the world, keep an eye out for some of other pegmatite rarities: stibiotantalite and columbite-(Mn)!  These minerals will occur as black to root beer brown colored crystals, usually with a somewhat flattened shape.  Some stibiotantalites even exhibit a beautiful color zoning!  These minerals, though lacking the vivid colors of some of your other possible finds, have a fascinating chemistry (they include rare elements like tantalum and niobium!) and are fairly rare in worldwide deposits – don’t throw them away!

Stibiotantalite on Tourmaline - 6.0 cm - photograph from Rob Lavinsky, iRocks.com

Stibiotantalite on Tourmaline – 6.0 cm – photograph from Rob Lavinsky, iRocks.com.

There are a few other minerals we haven’t mentioned (mostly because they’re super rare or uninteresting or both), but you can see a complete list and more photos on mindat.org here: Himalaya Mine, Gem Hill, Mesa Grande Mining District, San Diego County, California, USA.


Dig info:

Himalaya Mine Finds! - photograph from Himalaya Tourmaline Mine

Himalaya Mine Finds! – photograph from Himalaya Tourmaline Mine.

So now that you’re ready to pack the car and go, here’s the rest of the important information you need to know!

The Himalaya Mine dig site is open year round on Thursdays through Sundays from 10am to 3pm (Monday digs can be arranged by reservation only).  The mine is located near Santa Ysabel, California and is open to the public.  Visitors can dig and screen through ore from the mine in search of pink, green, and black tourmaline, quartz, garnet, lepidolite, cleavelandite, and more!

Screening for Gems - photograph from Himalaya Tourmaline Mine

Screening for Gems – photograph from Himalaya Tourmaline Mine.

The cost for adults is $75/day, 13-15 years old is half price ($37.50/day), children 12 years and under are free with a paying adult, and additional children are $20/day.  Senior and active military discounts, rain discounts, and group rates are available.

Be prepared to go digging: it’s going to be dirty and weather is going to happen.  Be sure to bring appropriate gear (sunscreen, raincoats, shoes that can get muddy, etc.) as well as food and water.  Sorting through material can be made easier with toothbrushes and rubber gloves.  Don’t forget baggies/buckets and wrapping material for your finds!

How to Get There:

LISTEN UP, FOLKS!  Do NOT use Google Maps or Map Quest to take you to the “Himalaya Mine” – this will NOT take you to the right location and you will end up LOST!

Instead, use the address Lake Henshaw 26439 Hwy 76, Santa Ysabel, CA 92070 to take you to Lake Henshaw Resort.  You will need to go into the store (across from the lake and in the same building as the restaurant), ask for the mine dig, and the cashier will give you a code and further directions.

Make use of the MAP provided by High Desert Gems & Minerals by clicking here.

Be sure to check out High Desert Gems & Minerals’ website for any further information on the dig: Himalaya Tourmaline Mine Dig.

Himalaya Mine Tourmaline - photograph from the Himalaya Tourmaline Mine

Himalaya Mine Tourmaline – photograph from the Himalaya Tourmaline Mine.

 

Collecting Tourmaline in Colorado – Brown Derby #1 Field Trip

‘curved’ Rubellite tourmaline crystal in Cleavelandite

The Brown Derby #1 Pegmatite, Gunnison County, Colorado- An unusual LCT-Type Pegmatite with Rubellite Tourmaline, Lepidolite and Rare Earth Element Species
Philip M. Persson
3139 Larimer St., Denver, CO, 80205
perssonrareminerals.com
Exploration Geologist

When it comes to Colorado pegmatite’s, most people think of the vivid and prolific smoky quartz and ‘Amazonite’ feldspar combinations or perhaps fluorite or topaz crystals from the Pike’s Peak batholith, which can be seen in collections all over the world. Tourmaline is certainly not a species that comes to most collector’s mind’s from the Rocky Mountains, yet Colorado does contain several unusual and interesting pegmatite’s of the ‘LCT’ (lithium-tantalim-Niobium) type which contain fairly high-quality (though not ‘gem’ in the pocket sense) tourmaline crystals along with other rarer species. The most notable and certainly the most studied of these deposits is the Brown Derby #1 Pegmatite, located in the Ohio City/Quartz Creek District, approximately 18 miles northeast of Gunnison in the high mountains of Central Colorado. First mentioned by Eckel (1933) and later by Staatz and Trites (1955) in their exhaustive study on the Quartz Creek Pegmatite District, this locality has long been of interest to both collectors and mineralogists. In recent years, however, due to a combination of property access issues, remoteness, and a shift in focus of Colorado collecting to ‘dig’ localities for smoky quartz, amazonite et cetera, the Brown Derby seems all but forgotten. This article is not an attempt to eclipse or duplicate the already extensive literature on this locality, but rather provide a modern and collector-oriented perspective on this fascinating deposit.

Quartz Creek Pegmatite District

Gunnison Colorado, where the Quartz Creek Pegmatite District is located


Quartz Creek Pegmatite District

Close up of the Quartz Creek Pegmatite District


Figure 1: Map showing location of Gunnison in Central Colorado (‘A’), with inset from Hanley et al. (1950) showing the Quartz Creek Pegmatite District, with the Brown Derby #1 Deposit marked with red star.

The Brown Derby #1 Pegmatite is the largest and most mineralogically-complex of a group of over 5 semi-parallel, dike-like pegmatite bodies which are situated on the western slope of a fairly prominent ~9400 foot high hill above the small settlement of Ohio City, approximately 18 miles northeast of Gunnison, Colorado, and 180 airline miles southwest of Denver. (Staatz & Trites 1955). According to Cerny (1991)’s pegmatite classification scheme, these are classic ‘LCT’ (lithium-tantalum-niobium) type deposits, and contain the geochemical and mineralogical characteristics of such deposits. They intrude ~1.7 billion year old metadiorite and associated metamorphic rocks of the Idaho Springs group, the Precambrian basement complex which covers a large portion of the State. Geochronology work by Heinrich (1967) and others found the pegmatite’s to be syngenetic to metamorphosis of the host rocks ~1.7 billion years ago, and they intruded as large sheet-like bodies parallel to the internal foliation and structure of the host rock. They strike N/NE and dip gently into the steep southeast hillside at 20-35 degrees (Heinrich 1967). The largest 3 pegmatite’s of the Brown Derby group all display exceptional mineralogical and geochemical zoning which is typical of most large LCT-type deposits, with the #1 Dike exhibiting the highest mineral diversity.

along the strike of the Brown Derby #1 Pegmatite
Figure 2: Looking Southeast along the strike of the Brown Derby #1 Pegmatite; large metal grate visible in center of photo is covering one of the underground drifts leading to a large stope on the core of the deposit. (Photo copyright Rudy Bolona/mindat.org)

Entrance to the #2 Tunnel, or main adit of the Brown Derby #1 Pegmatite
Figure 3: The Entrance to the #2 Tunnel, or main adit of the Brown Derby #1 Pegmatite, showing the sharp contact between pegmatite (white rock) and overlying metadiorite (dark gray) at the hanging wall contact. (Photo copyright Rudy Bolona/mindat.org)

The #1 Pegmatite was developed from the early 1930’s through the 1970’s and was mined principally for the lithium content of lepidolite, along ceramic-grade feldspar, minor beryl, and a somewhat substantial production of microlite, a tantlum species, though it is unclear if the resulting microlite concentrate was ever processed (Heinrich, 1967). It is presently divided into two properties in legal terms; a large surface exposure with associated dumps, which sit on National Forest/BLM land and are open to mineral collecting, and a fairly small underground portion which is owned by a group which identifies themselves as ‘Precious Offerings Mineral Exchange, LLC’ and is based in Boulder, Colorado. They are involved in Bureau of Mines-mandated remediation work on the underground workings of the Brown Derby #1 Mine, and as their willingness to allow collectors underground is not presently known. The author does not want to encourage activity which may compromise their remediation efforts; therefore this article will focus on specimens and species which can be collected from surface dumps and exposures, of which there are many. Hopefully in the future, the owners of the underground mineral rights will allow collectors to participate in their efforts to recover specimens from this unusual deposit.

This photo is a CRAZY AMAZING Tourmaline with RICH RED COLOR and 5 big crystals standing tall and unbelievable on a bit of matrix

While Tourmaline crystals like this can not be found here, you can see plenty of amazing photos by clicking on this photo of a Brazilian Tourmaline cluster!

The Brown Derby Mine is best approached from U.S Highway 50 from a small turnoff approximately 6 miles east of the small settlement of Parlin and 17 miles east of Gunnison. Turn north here onto Forest Service road 802, also locally marked as the 44 Road. From here, continue north ~1.5 miles, bearing right at the ‘Y’ onto 802 north where some small granitic-looking outcrops start to become visible on your right. Continue on this fairly good dirt road north/northeast past a small stream crossing (may not be passable to passenger cars after recent rain or in the spring) and ~1 mile after the stream crossing, bear left at another fork up an obvious large ‘humpback’ like sagebrush-covered hill, passing a cattle fence (please respect local ranchers and close gate after your drive through!). Continue on this steepening road for another ~1.5 miles over somewhat rough terrain (4 wheel drive/AWD necessary, though high clearance is not mandatory for this section) until you reach a large flat ridgeline with small aspen trees in a grove on your left. This is a good camping spot. Continue until the road apparently disappears into the sage rush, then pick up another fairly good dirt road leading steeply downhill to the left/west towards now fairly obvious white pegmatite mine dumps below you. Continue down past several switchbacks to an eventual right turn through an open gate to a mine access road leading past an abandoned shack where core samples were stored/examined. The large dumps below you and the large gated adit to your right are the Brown Derby #1 Mine.
Tourmaline: Tourmaline is found in an impressive range of colors and several species at the Brown Derby #1 Mine. Of primary interest to collectors are large crystals and sprays of Elbaite variety Rubellite, which ranges from a dull whiteish-yellow color to choice ‘hot pink’ crystals reminiscent of Transbaikal, Russia or Stewart Mine, California rubellite crystals in color. While generally not gemmy, rare crystals to several cm. are found frozen in lepidolite and cleavelandite matrix, which do show gemmy, clear sections that could potentially yield small gems. An early 1970’s Denver Post article reported gem-quality elbaite in small amounts from the Brown Derby Mine (Eckels 1997), but the author has not seen any of this material in collections or institutions. Most impressive and aesthetic are radiating ‘sprays’ of parallel to sub-parallel pink Rubellite crystals set in coarse purple lepidolite matrix, with individual rubellite crystals up to 15 cm. or more in length. Early reports indicate that in several ‘pods’ in the core of the pegmatite, ‘logs’ of elbaite tourmaine crystals up to 30 cm. long showing ‘watermelon’ zoning with rubellite surrounding an elbaite core were found. The author has personally seen well-formed crystals up to 20 x 5 cm. in place. Also interesting are elbaite crystals which are either partially or fully psuedomorphed by lepidolite or muscovite, which are locally common. Large masses of tightly intergrowth elbaite crystals showing an amazing color gradation from lime-green to yellow to pink to reddish within a single crystal were also found fairly commonly (Staatz & Trites 1955). Staatz et al. (1955) looked at the geochemical variations within these crystals as a guide to color and color gradation, as well at petrogenesis of the pegmatite as a whole. Schorl is also found fairly abundantly at the Brown Derby #1 Mine, where it occurs in the wallzone and outer intermediate zones of the pegmatite, generally in subhedral to poor crystals, sometime radiating outward into the metadiorite.

Rubellite tourmaline crystals in quartz
Figure 4: 4 cm. long, slightly gemmy hot-pink Rubellite tourmaline crystals in quartz with partial rubellite crystals surrounding it, Brown Derby #1 Pegmatite.

‘curved’ Rubellite tourmaline crystal in Cleavelandite
Figure 5: Naturally ‘curved’ Rubellite tourmaline crystal in Cleavelandite and lepidolite. Curvature resulted from tectonic movement in pegmatite during crystallization. Scale in cm.

radiating pink Rubellite crystals to ~5 cm
Figure 6: Spray of radiating pink Rubellite crystals to ~5 cm. in fine-grained lepidolite and quartz, similar to Stewart Mine, California material. ~15 cm. field of view.

‘polychrome’ tourmaline
Figure 7: Good example of massive to coarsely-crystalline ‘polychrome’ tourmaline with gradation from pink to green to yellow, showing some translucent to slightly gemmy sections. Field of View 15 cm. across.

Lepidolite: Second after tourmaline in interest to collectors, and arguably more famous from the Brown Derby Mine is Lepidolite, the violet-colored lithium mica, which occurs here as ‘books’ and crystals to over 10” across! Books of lepidolite several inches across are common, and even 6” crystals are not unusual. Masses of nearly solid lepidolite 5-10 feet across can be observed in places in the pegmatite. Lepidolite along with other mica’s at the Brown Derby Mine were studied by Heinrich (1967), who also noted muscovite, zinnwaldite, and polylithionite, though the occurrence of the latter is questionable. In addition to the large tabular hexagonal ‘books’, lepidolite also occurs as large masses of fine-grained, equigranular crystals to several mm., which generally host more unusual species such as microlite or monazite. Finally, an unusual variety known as ‘ball lepidolite’ occurs locally in hemispherical masses up to 15 cm. composed of rounded, subparellel crystals, which supposedly have been worked into cabachons and other lapidary items. All lepidolite from the Brown Derby #1 Mine shows a handsome rich purple color and a generally bright luster.

Lepidolite to 15 cm
Figure 8: Large books of Lepidolite to 15 cm. across in quartz-cleavelandite pegmatite, hand for scale.

Monazite-(Sm): In addition to fairly common mineral like elbaite and lepidolite, the Brown Derby #1 Mine is also unusual in it’s concentration of more unusual rare earth element (REE) species. Arguably the most interesting of these is the recent discovery of Monazite-(Sm), though the possibility of this species at the Brown Derby Was first noted over 50 years earlier by the always astute E.M Heinrich (1960), who analyzed several monazite samples from the Brown Derby #1 Mine containing >10% Samarium(!) Colorado field collector and REE specialist Rudy Bolona collected several specimens of brownish-red massive Monazite associated with white Cleavelandite feldspar and lepidolite from a single boulder on the dumps in 2009, and subsequently has a sample sent to Dr. George B. Morgan at the University of Oklahoma, who analyzed it to be the very rare species Monazite-(Sm), found only at 3 other localities worldwide. While all monazite samples from the Brown Derby #1 Mine analyzed by Heinrich (1960) appear to contain enough Sm to qualify as Monazite-(Sm), Monazite-(Ce) also occurs at this deposit, so it is not safe to assume that all monazite collected at the Brown Derby #1 is Monazite-(Sm). Monazite-(Sm) occurs at the Brown Derby #1 Pegmatite as subhedral masses to crude crystals up to ~6.5 cm. across, typically embedded in fine-grained lepidolite with cleavelandite feldspar and quartz. The Brown Derby #1 occurrence may represent the best locality in the world for this rare species, and new finds of this rare mineral are possible on the extensive dumps.

Monazite-(Sm)
Figure 9: Massive reddish-brown Monazite-(Sm) (analyzed) with purple lepidolite, 6.8 cm. across. (Photo copyright Rudy Bolona/mindat.org)

Pollucite: The Brown Derby #1 Pegmatite represents the only Colorado locality for this rare cesium species, which occurs as two large, ~30 cm. wide massive pods in the central core zone of the pegmatite, along with large crude crystals of opaque topaz, cleavelandite, and quartz (personal communication with Rudy Bolona, September 2009). No crystallized material is known, nor has this mineral been reported from the dumps.

Massive white crystalline Pollucite
Figure 10: Massive white crystalline Pollucite, 6.5 cm. across. (Photo copyright Rudy Bolona/mindat.org)

Stibiotantalite: Stibiotantalite is a rare Antimony Tantalum Niobium Oxide species found in LCT-type pegmatite’s and was first described from the Brown Derby #1 Pegmatite by Heinrich & Giardini in 1957. It occurs as subhedral to poorly euhedral crystals generally 1-2 cm. but rarely up to 5 cm. associated with the secondary Tantalum species Rynersonite as a white to cream surface alteration of the stibiotantalite. Heinrich & Giardini found stibiotantalite on a large boulder on the dumps of the #1 Pegmatite, and thought that possibly all the stibiotantalite in the #1 pegmatite was contained in this single block, a large mass of cleavelandite, topaz and lepidolite from the core margin core. However, recent finds of small Stibiotantalite crystals by Colorado collectors on the dumps would argue otherwise.

Well-formed 8 mm. long Stibiotantalite
Figure 11: Well-formed 8 mm. long Stibiotantalite crystal on lepidolite-cleavelandite pegmatite, collected recently on the dumps. (Photo copyright Rudy Bolona/mindat.org)

Columbite-(Fe): Columbite-(Fe), the Fe-analogue of the Niobium oxide species Columbite, is found in several assemblages at the Brown Derby #1 Pegmatite. In the core margin zone of the pegmatite, it is found with Cleavelandite feldspar, quartz, and mica minerals as large, crudely euhedral crystals to 10 cm. In the border zone of the pegmatite, especially towards the hanging wall contact with the metadiorite, it is found as small (<5 cm.) grains and crude crystals associated with reddish albite/perthite, Euxenite-(Y), and Monazite-(Ce). Nowhere at the Brown Derby deposit is Columbite-(Fe) an especially common nor conspicuous constituent, however it does occur through a wide portion of the pegmatite. Columbite-(Fe) in albite
Figure 12: Partial crude crystal of Columbite-(Fe) in albite, 8 x 6 cm. (Photo copyright Dean Allum/mindat.org)

Euxenite-(Y): A glassy green metamict Rare Earth species, previously identified as Betafite in some literature, is now believed to be Euxenite-(Y) (Heinrich 1967). Euxenite-(Y) is restricted in occurrence at the Brown Derby pegmatite to a core-margin albite replacement near the upper north margin of the core, but may exist in other unrecognized or mined-out zones as well. It occurs here as metamict masses to 4 cm. in weathered red albite with schorl and columbite-(Fe), and is highly radioactive.

Monazite-(Ce): Monazite-(Ce) occurs at the Brown Derby #1 pegmatite in several assemblages, making non-quantitative distinguishing from Monazite-(Sm) difficult to impossible. It is found as fairly sharp euhedral crystals to ~2.5 cm. in red albite with columbite-(Fe), probably from an analogous assemblage to the aforementioned Euxenite-(Y) zone. The Harvard University Mineralogical museum has several excellent crystallized specimens, one of which (HMM #104814) is pictured here.

Monazite-(Ce) to 2.4 cm. in perthite-albite-biotite pegmatite, Harvard Mineralogical Museum
Figure 13: Well-formed crystals of Monazite-(Ce) to 2.4 cm. in perthite-albite-biotite pegmatite, Harvard Mineralogical Museum #104814.

Microlite: Microlite, the complex tantalum oxide species, is known from several zones of the Brown Derby #1 Pegmatite and was one of the significant economic minerals of this deposit, though the present distribution of microlite in the dumps and in-situ would suggest otherwise. This is probably due to the fact that microlite occurred in concentrated ‘shoots’ or elongated pods in fine-grained lepidolite-quartz-cleavelandite pegmatite, a mode of occurrence similar to that at the famous Harding Pegmatite in New Mexico. These ‘shoots’ were mined selectively for their microlite content, and ~1200 pounds of Microlite was concentrated and stockpiled for processing, though it is unclear if this material was ever actually sold (Hanley 1950). Hanley also estimates that ~9,000 lbs. of microlite remained at the time of his study in 1944 at the Brown Derby #1, though it is unclear how much of that has been mined since. Mineralogically, microlite forms small crude to somewhat euhedral octahedral crystals to 1 cm. with a resinous brown to black luster and distinctive radiation ‘burn halo’s’ in the surrounding lepidolite. These crystals are often quite radioactive and may in fact be uranomicrolite.

Microlite in crude 3-4 mm. crystals in fine-grained purple Lepidolite
Figure 14: Microlite in crude 3-4 mm. crystals in fine-grained purple Lepidolite; specimen 4 cm. across. (Photo copyright John Betts/mindat.org)

Other accessory species: For the sake of brevity as well as the fact that they do not occur in ‘collector-quality’ crystals, other species such as Topaz, Beryl, Garnet, and Bismutite will not be discussed in detail here. Suffice it to say that they are present at the Brown Derby #1 Pegmatite, and a quick search of the already extensive literature on this deposit will yield many interesting references.

In closing, the Brown Derby #1 Pegmatite remains one of the more interesting and unusual pegmatite deposits in Colorado, and unlike many similar localities, a large portion of the dumps as well as surrounding prospects remain both on public land as well being as accessible to vehicles. The Brown Derby #1 deposit is also unusual in that while it continues to yield excellent, aesthetic specimens of relatively common minerals such as Rubellite tourmaline and lepidolite, finds of extremely rare species such as Monazite-(Sm) have also been made recently. If you plan to visit from Brown Derby #1 Pegmatite, please be respectful of local claim holders and property owners and exercise safety and common sense around the large dumps and potentially dangerous mine faces and outcrops. With persistence and luck, this locality should continue to yield great mineral specimens for many years to come.

References
1.) ‘Mica’s of the Brown Derby Pegmatites, Gunnison County, Colorado’, Heinrich, E.M, The American Mineralogist, Volume 52, July-August 1962.
2.) ‘A New Lepidolite Deposit in Colorado’, Eckel, F.B., American Scientific Society, 16, pp. 239-245.
3.) ‘Lithia Pegmatites of the Brown Derby Mine, Gunnison County Colorado’, Hanley, John B., 1946, American Mineralogist 31, 147.
4.) ‘Pegmatite Investigations in Colorado, Wyoming and Utah: 1942-1944’, E.M Heinrich et al., USGS Professional Paper Paper 227, 1950.
5.) ‘Stibiotantalite from the Brown Derby #1 Pegmatite, Colorado’, Heinrich, E.M & Giardini, A.A., American Mineralogist 45, pp. 728-731, 1960.
6.) ‘The Quartz Creek Pegmatite District, Gunnison County, Colorado’, Staatz, M.H. & Trites, A.F., USGS Professional Paper 265, 1955.
7.) ‘Paragenesis of the Topaz-Bearing Portion of the Brown Derby #1 Pegmatite, Gunnison County Colorado’, Rosenberg, P.E., American Mineralogist 57, 571-583, 1972.
8.) Mindat.org, accessed 8-01-2013 to 8-15-2013.