Tag Archives: zeolites

Sea Cliff Zeolites at Oceanside, Tillamook County, Oregon – A Zeolite Tutorial

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Volcanic Basalt Lava is found all over the world. Often the host for beautiful minerals and crystals of quartz, calcite, agate and a host of zeolite minerals. The Amethyst deposits of Southern Brazil/Uruguay are considered the best quartz in basalt find, as are the fine Zeolite deposits of Southern India. Before India, many places were considered to be the world’s best zeolite deposits, like Scotland or Iceland.

It just goes to show, deposits of minerals in basalt rock deposits are well worth searching out in your local area. Consider the volcanic basalts of Oregon/Washington. Beautiful examples of rare and exotic minerals were once only known from these basalts, including, shockingly to some collectors, Cavansite!

Small Cavansite crystals on matrix from the type locality in Oregon

Specimen of Cavansite from the first place it was found, in Oregon. Zeolite deposits found in volcanic deposits are well worth inspecting for rockhounding possibilities!

Found in volcanic lava that has interacted with water, zeolites are beautiful minerals which are found in a huge diversity of different appearances. They are known to form where enormous volcanic events have occurred in the ancient past when lava flows into a body of water.

The lava instantly chills, creating a unique bubbly, rounded texture called pillow basalt where within spaces between the rounded “pillows” grow delicate crystals of zeolites as steam chemically leaches the basalts and forms new minerals.

Steam may rise through the molten lava as well, where the rock may solidify before it escapes. This type of rock is called a vesicular basalt. Many minerals tend to form in the “bubbles” or vesicles in this type of rock.

Pillow Basalt that zeolites are found in

A recently formed pillow basalt at the Galapagos Rift versus an ancient pillow basalt in the Bonin Islands, Japan. Zeolite minerals are found between the “lobes” of the lava.
A vesicular basalt boulder. The holes are known as vesicles and represent where rising gasses got trapped in the rock. Minerals often form in these vesicles.)

The Cape Lookout area is the remains of a volcanic island that emerged in the Miocene period, about 16 million years ago. Cracks in the earth formed, releasing lava into the sea which cooled on contact with the water, forming pillow basalts and bubbly vesicular basalts which further altered to form zeolite minerals in the pores.

Many rare zeolites are found here, not the ones you would typically see in the large, flashy specimens from India many collectors love, but equally as beautiful if you can appreciate tiny things. Minerals you may encounter are erionite, mordenite, clinoptilolite, and dachiardite. Often these are found with calcite and clay minerals, the latter can give specimens some nice color and visual depth.

Specimens from this area are typically small, but absolutely stunning especially under magnification. A good, readily available microscope to view your microminerals with is the Dino-Lite, which you can attach to your computer via USB.

A Dino-Lite digital microscope.

On this page, our focus is on two collecting sites you can visit, though exploring the beach may yield many more discoveries. Keep an eye out for sprays and nodules of zeolite minerals in the rock, much of which occurs in vesicular basalt, which looks like Swiss cheese.

The first area is Short Beach. There should be a stairway near a creek where you can access the rocky beach below. Here you will find boulders of vesicular basalt that you can break up to yield minerals in the vesicles.
Bring a pocket lens or loupe with you so you can more easily see minerals in the vesicles. They will be somewhat obvious, appearing as white puffballs and sprays, but some may be more hidden.

There is said to be better collecting even still at Tunnel Beach, down the road to the south.

North of the tunnel, you will see pillow basalt cliffs. Formed as lava was ejected into the sea, these cliffs and the surrounding boulders are rich in zeolites and offer some of the best collecting in the area. Use the tunnel to access the beach.

Minerals: These localities are heaven especially to the micro-mount collector. Some beautiful photos of material from the surrounding area are on Mindat (these are copyrighted and we don’t care to hotlink, just click the links for some great photos).

Embed:
https://www.mindat.org/photo-750805.html
Caption: Found by Rudy Tschernich, famous PNW zeolite collector. 14 mm FOV Golden erionite hemispheres on a white backdrop, looking like a fried egg with a broken yolk
https://www.mindat.org/photo-750632.html
Tiny, bushlike mordenite in a tiny vesicle from Tunnel Beach. Found by Rudy Tschernich
https://www.mindat.org/photo-257230.html
About a 1 inch wide plate of green gray clinoptilolite on mordenite from Short Beach, collected by Bill Tompkins
https://www.mindat.org/photo-751603.html
Tiny, about 2.5mm vesicle of delicate golden erionite sprays. Found by Rudy Tschernich

Collecting Zeolites: To do the best job you can collecting these delicate specimens, you will need to be prepared to break the hard basalt rock. Use a heavy crack hammer and a chisel to smash the boulders open, revealing fresh material. Zeolites are extremely delicate and the freshest, nicest ones will be found unexposed inside the rocks.

As said above, loupe or hand lens will help you see what’s going on inside the tiny vesicles a lot better. Some of the most beautiful specimens from this location are extremely tiny so you may miss them without a lens.

Remember to wrap your specimens very carefully. Many of these specimens are extremely delicate to the point that even blowing on them may damage them. Do not wash anything very velvety, hairy, or puffy or even moisture can mat and destroy the crystals.

You will have to time your collecting with the tides at these locations. Be aware of the tides and weather conditions before you go to the beach and collect.

More Info:
https://www.mindat.org/loc-210854.html
https://www.mindat.org/loc-205422.html
https://www.netartsbaytoday.org/html/zeolites_of_oceanside.html

And, if the Cavansite deposit sends your imagination wild, check out this article:
https://www.mindat.org/article.php/964/Field+Trip+to+Cavansite+Type+Locaility

Agate Collecting in Colorado – Wolf Creek Pass Zeolites

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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!