Agate Collecting in Colorado – Wolf Creek Pass Zeolites

Near the border of Archuleta County in Colorado, Wolf Creek Pass and Treasure Mountain contain a deposit of silicates and zeolites that have made their way into mineral collections around the world. The collecting area, spread out over the rocky mountainside, is often referred to as Wolf Creek Pass. However, Wolf Creek Pass is actually a 10,000 foot mountain pass that wraps around Treasure Mountain and follows the Wolf Creek. The mountain does not bear gold or jewels, but the volcanic basalt deposits are near a very photogenic waterfall, Treasure Falls. Surrounded by scenic views, this basalt deposit is one of the most thrilling areas of Colorado. Hotels.com has great deals on hotels around Wolf Creek Pass, Colorado

Quartz specimen with banded agate and a crystal center with a slight purple hue.
Quartz specimen with banded agate and a crystal center with a slight purple hue.
Photo by Mathew Marulla (marulla.com)

Treasure Mountain is named after the legendary stash of gold, left behind by a French expedition in 1790. Several search parties have tried to find the fortune of gold bars acquired from a gold deposit near the Peak of Treasure Mountain, but none have been successful in finding the bars or the deposit.

Much of the collecting area is adjacent to highway route 160 and in the boulders and exposed rock of the mountainside just north of the falls. The mineralized area is fairly large and boulders containing the material have been distributed across the area, both naturally and due to the construction of route 160 and Wolf Creek Pass. In fact, due to the close proximity to Archeuleta county to the south, part of the deposit crosses this manmade border separating the counties which only serves to cause confusion in geographic labeling of specimens from this deposit.

Map of the Treasure Creek Agate and Zeolite location
Map of the Agate and Zeolite locations around Wolf Creek.

Rounded amygdaloids fill the voids in the volcanic deposit of basalt, as with many occurences. These host crystals of quartz and about half a dozen zeolite minerals.

The quartz and agate are similar to that found in many other volcanic silica deposits. The agate is typically clear, white and/or shades of blue, often with alternating layers that make it desirable for lapidary use. Some have crystallized centers. Typically the crystals form on a layer of agate, which varies in thickness from miniscule shells to thick rinds. Sometimes the crystals are amethyst, making attractive specimens on dark colored volcanic matrix. Though the agate and quartz found here do not rival that found at many other locations, it is one of only a few still open for collecting.

Of course, the zeolite species are what makes the location a true Colorado classic. Analcime is typically found as very small crystals usually below 1 cm in size. However, at one location, analcime is found up to 3.5 cm. Chabazite occurs here, but not in crystals larger than a few millimeters in size. Heulandite is sometimes found as crystals up to 5 cm across. However, typically the crystals are only millimeters in size, lining the cavities and serving as matrix to other minerals. One such mineral is mordenite, which is found as well formed clusters of white fibers. These clusters, up to a few centimeters in size, were referred to as being one of the best locations for the species in the United States for many years.

Mordenite crystals in a vug of basalt
Mordenite crystals in a vug of basalt
Photo by Mathew Marulla (marulla.com)
Mordenite Crystals up to 2 cm long can be found at the location
Mordenite Crystals up to 2 cm long can be found at the location
Photo by Mathew Marulla (marulla.com)

Other associated minerals include globular common opal, small rhombs of calcite, and small pyrite crystals. The locality is also a classic locality for the clay minerals celadonite and nontronite, which form in abundance. Laumonite, natrolite and wellsite also occur in the deposit, but they occur rarely and only as small crystals

Isolated Heulandite crystal on matrix.  Specimen size is 6 millimeters
Isolated Heulandite crystal on matrix. Specimen size is 6 millimeters
Photo by Luigi Mattei
Several voids filled with celadonite
Several voids filled with celadonite overall size 10 x 5 x 3 cm.
Photo by Martins da Pedra

Due to the vast deposit and mountain conditions, this source of colorful quartz, agate and zeolites will always exist in the mountains of Colorado. Maybe the lack of gold is a bit disappointing for a mountain with such high aspirations, but to many mineral collectors around the world, the real treaures are the mineral collecting opportunities and the often-visited Treasure Falls.

If you enjoyed this article, it was originally printed in The-Vug.com Magazine, which was released as a hardcover coffee table book, collecting all 16 issues of the original magazine. It is 324 pages, hardcover and full color, available directly from the publisher at FortySevenPress.com For $34.95, it is full of great photos, articles, collecting locations and more! Get your copy to add to your mineral book library!

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Cummingtonite – We know you were looking for iron rich amphiboles…

As mineral collectors on the internet know, the jokes can often lead back to one mineral.
Cummingtonite. Eliciting snickers in a room of freshmen geologists (and honestly, still getting chuckles from aged field geologists under the right conditions). Lately it is the most popular iron rich amphibole mineral to be searched for on Google. We all know when we see that fact it is not because people are looking for their favorite ugly brown rock! Most minerals are searched for their beauty, this mineral can only claim its name as the claim to fame.

Cummingtonite is a rather uncommon mineral, hailing from the riverside on the far western edge of Cummington, Massachusetts. Here is a sample of the mysterious brown crusty amphibole they were mining. Scratching their heads, someone noticed this as an unknown mineral and dubbed it Cummingtonite, in honor of the town it was found. This is often the case, such as Elbaite, Annabergite, and Boleite.
Thick vein of Cummingtonite
Cummingtonite with label from original find
Cummingtonite Specimen
Garnets and Cummingtonite
This specimen pictured is from the Philadelphia Academy of Natural Sciences. It shows a chunk of brown radiating crystals with embedded garnets. Donated by a prominent American Mineralogist Charles Upham Shepard, a man who submitted the approvals for Danburite, Microlite and others. He had one of the largest collections of minerals in the United States, donating specimens to various museums in life and death. He was a well respected lecturer on subjects of Natural History. Charles Upham Shepard graduated from Amherst College in 1924, the same year that Cummingtoite was accredited.

1824. Cummingtonite. (Dewey.)
“I have here given this name to a mineral found by ‘Dr. J. Porter in
Cummington. It appears to bo a variety of epidote. Its color is gray,
sometimes with a faint reddish tinge, unless when acted on by the
weather, when its color is yellowish. It is in distinct prisms, with oblique
seams like’ zoisite, and in radiated or fascicled masses, which are com-
posed of slender prisms. Luster somewhat shining or pearly. It is nearly
as hard as quartz, and sometimes makes a slight impression upon rock
crystal. Before the blowpipe it blackens, and a small portion melts, when
the heat is very great, into a black slag, which ik attracted by the mag-
net. With quartz and garnet .it forms a largo mass in Cummington.”
C. Dewey : Geol. Min. Mass.; Am. Jour. Sci., 1st series, Vol. VIII, p, 59.
1824. Cummingtonite. Lies by the roadside in the east part of
Cumnimgton.
Known to the common people for several years under the name.of copperas
rock; occasionally used in dyeing as a substitute for sulphate of
iron.
J. Porter: Min. Loc.; Am. Jonr. Sci., 1st series, Vol. VIII, p. 233.

Cummingtonite, the inspiration for snickers, memes and lame t-shirts, has a much more benign beginning!

With your knowledge of what Cummingtonite is, beyond a cleaver play on words, now I will tell you how you can go collect your very own specimen, along with brightly colored Lepidolite mica, UV reactive opal hyalite and shiny Hematite crystals. Far off in the desert of Arizona, nobody will hear your terrible off color humor besides your collecting partners. If you’ve ever been collecting petrified wood with a group of geologists who loudly exclaim “I’VE GOT WOOD!”, you have an idea of what to expect.

The location to collect Cummingtonite is just off to the north of the BBC Mine, a half hour away from Parker, Arizona.
The area is a wonderland of mineral collecting, with the BBC mine area boasting FINE crystals of Hematite, sometimes assosicated with Chrysocolla. Further to the North is the Planet area, filled with Barite, Malachite, Chrysocolla and all sorts of beautiful minerals. Fluorite, Gold and more copper minerals are found within 20 miles of this location, so beyond the oddball amphibole Cummingtonite, there are plenty of reasons to visit this area!

Map to Cummingtonite deposit
Map to Cummingtonite deposit
Open trench at cummingtonite deposit - Watch Your Step!
The location is a simple series of trenches, where you can find a very odd form of Lepidolite, normally known as being bright purple, here it is yellow. The hematite at the cummingtonite location is not nearly as nice as the hematite at the BBC mine. <---click to view photos on MinDat.org

Cummingtonite on matrix from Arizona

The material from here is not even a tenth as nice as the crunchy material from Massachusetts, however, being able to collect your own specimen of this odd, uncommon material, is something to get excited about! ;)

If you would like a more “in-depth” view into this collecting location, let me advise you to check out the excellent Android App that will guide you to several locations around the Quartzsite/Parker area. Download this Android App for $4.99

We love you readers so much that we provided a google map pointing you to the locations.


View Cummingtonite and BBC Mine in a larger map

And I’m not completely innocent on the juvenile jokes…I am the proud owner of a Dickite specimen from Beaver Creek. ;)

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