Singing The Blues
The story of a rare Northwest gem chalcedony
There are many occurrences of blue chalcedony that have been discovered, mined, and marketed around the world. Africa has Malawi and Namibian Blue Lace, Turkey has Anatolian Blue, and Oregon is well known for Holley Blue which is more often lilac colored rather than blue. Another occurrence that is very well known in the Pacific Northwest and also one of the rarest forms is called Ellensburg Blue for the town it was named after. This distinctive blue chalcedony has been eagerly sought by rockhounds for years in the hills north and west of Ellensburg, Washington. Polished and often free-form cabochons of this material grace many a finger, ears, or neck of those wishing to make a fashion statement. It comes in a color range from light blue to a deep purple-blue and exhibits a very attractive pinkish glow when viewed from the side. It also transmits subtle skin tones from the wearer due to the translucency of high quality material. There is an abundance of confusion and misinformation circulating about what constitutes “real” Ellensburg blue agates and where they can be found. Some of this information is good and some is not so. There are also numerous instances of blue agate being offered for sale on the internet that are being called Ellensburg Blue, but are not. Being able to distinguish between the real deal and the knockoffs is important when Ellensburg Blue is now, in some cases, being sold by the carat.
Maybe a good place to start this story is to first talk about some of the important geological events that led to the formation of Ellensburg and other types of chalcedony that can be found in the area. When traveling north and west from the city of Yakima, Washington along Interstate 82 you crest the east/west trending Manastash Ridge and are greeted by a stunning view of the Kittitas Valley with its extensive green fields of rye grass that stretch away into the distance. Higher up on the north slopes of the valley the shrub steppe grasslands give way to the forest covered mountains that are part of the Wenatchee National Forest. Also in the distance is the imposing Mount Stewart Range which is the remnants of a massive snow covered granite batholith that originated somewhere west of the ancestral coast of Washington State. It rafted to its current position by being carried on the Juan de Fuca oceanic plate that is still subducting beneath the North American continent. The geology of this area is both complex and quite diverse. The front range north of Ellensburg consists of a formation called the Teanaway Basalt. It was extruded via dikes into a pre-existing Eocene Age formation called the Swauk which consists of repeated layers of conglomerates, sandstones, and shales. These layers were deposited during the Eocene when the climate was much warmer and the Cascade volcanoes had yet to form. In the area of Liberty, Washington, Teanaway basalt dikes injected gold bearing solutions into the Swauk Formation shale layers forming concentrations of wire gold. (See my July 2009 Rock & Gem article titled “Liberty Wire Gold”.) At another locality between the town of Liberty and Blewitt Pass on Hwy 97 the Teanaway basalt exposed at Red Top Mountain is well known for its numerous teardrop and potato shaped chalcedony nodules and crystal lined geodes. At yet another Teanaway basalt outcrop along Hwy 97 between Ellensburg and Liberty, called First Creek, complex geodes with quartz and calcite crystal linings can be found. (See my December 2013 Rock & Gem article titled “”First Creek Geodes and Agates”.) In both of these localities the geodes formed in gas bubbles in the cooling basalt. Chalcedony from these localities is often confused as being Ellensburg Blue because some of it can have a gray-blue appearance.
True Ellensburg blue chalcedony (agate) which is found in the same Teanaway basalt formation, but at a different location, formed in a different way. Rather than being deposited as infillings in gas bubbles the Ellensburg blue agate formed in seams when silica laden hydrothermal solutions invaded fractures in the cooled basalt. The difference in the depositional environment caused structural differences in the chalcedony on the microscopic level as the silica came out of solution. This led to the distinctive blue color these agates are known for. Research conducted by Dr. Paul Hoskin, formerly from Central Washington University in Ellensburg, Washington, found that the blue hue of the agates is caused by the interaction between light and minute spherules that make up the silica matrix. This is different than the trace minerals that often impart vivid colors to other types of agates. You can check out his lecture on the topic on YouTube. Another good source of information can be found by doing a YouTube search for videos on Ellensburg blue agates that have been posted by Central Washington University geology staff member Nick Zentner. He has become quite a celebrity with his frequent and well attended downtown lectures on a variety of Northwest geology topics and also his way cool field trips. Nick Zentner also has a popular PBS series (Nick on the Rocks) where he travels to different Washington state localities to film and talk about geologic features. He has posted a full catalog of his lectures and field trips on Youtube also. They are well worth checking out as his easy going presentations make geological complexities quite understandable.
Besides where and how Ellensburg agates formed, another topic to address is how Ellensburg blue agates can be distinguished from other types of blue agates like those listed earlier in this article. Dr. Angela Halfpenny from the geology department at Central Washington University is currently conducting research on that very topic. She is using an X-ray fluorescence technique that can analyze trace elements in the different varieties of blue agate to see if each possesses a distinctive fingerprint that can be used to tell them apart. I first saw Dr. Halfpenny demonstrate her X-ray florescence equipment when a team of professors and students from the geology department came down to Yakima in 2018 when we were hosting the Northwest Federation show. They put on numerous demonstrations, with one being a really cool volcano eruption simulation and another being how they use X-ray fluorescence to study the trace element makeup of rocks. Robert Langford, who is a member of our Yakima Rock and Mineral Club and owner of Langford Jewelers and Lapidary, approached her and asked if she would be interested in studying the Ellensburg gate cabochons he was offering for sale at his table. Robert specializes in cutting and setting Ellensburg agates. He was curious to see if her technique could distinguish Ellensburg agates from other types of blues. Robert has said that he is approached frequently by people wishing to sell him rough that they are calling Ellensburg Blue. He has told me in the past that being able to distinguish what is and is not in a quick and non destructive way would be most helpful and brings much needed quality control to the sale and purchase of the expensive agate. Since that meeting, Dr. Halfpenny has been working collaboratively with both Robert and a jewelry business from the Seattle area, Carlson Jewelers. The Carlson family both mine and create one of a kind jewelry pieces from the material they are recovering. Dr. Halfpenny has been testing Holley Blue, Namibian, Malawi, and Turkish Anatolian Blue to see how their trace element components compare. Preliminary results from her research are showing that the trace element signature from the Ellensburg agates is distinctive and unique when compared to other types of blue agates, which is good news.
The printouts from X-ray fluorescence tests comparing trace element signatures for Ellensburg Blue and Holley Blue agates show that they are strikingly different.
Seekers of Ellensburg Blues, or Eberg Blues as they are called by some, are hunted most heavily in the spring after the snow melts and when frost heaving occasionally brings new material to the surface. For anyone interested in going out to find their own treasure the news isn’t good. The area that hosts the seams where the agates formed has been under claim by the Carlson family for over 37 years and thus is off limits to collecting. An alluvial fan that emanates from a “notch” in the front range north and west of Ellensburg called the Green Canyon notch contains agates that weathered out of the seams and were carried down slope during and after the Pleistocene glaciation. Avid hunters have tromped this area for years in pursuit of the occasional find. Unfortunately much of this area has been sold off for ranchettes and thus is now in private ownership and off limits to collecting unless you can find an owner who will grant you access. One holding called the Rock N Tomahawk Ranch does allow collecting. For a nominal fee rockhounds still find the occasional agate, especially in the spring right after snow melt. Spring also brings out hordes of ticks so be prepared for that.
I am intentionally being rather vague with locality data where Ellensburg blue agates can be found. Remember, most of the areas that host this material are either under claim or on private land. Always ask permission before entering a piece of property, and make sure you know who owns the parcels you would like to explore.
I am very excited to see and be part of the collaborative effort between staff from the geology department of Central Washington University and individuals who wish to establish a way to identify Ellensburg blue agates. If the research Dr. Halfpenny is pursuing with the input of Carl Carlson and Robert Langford continues to bear fruit, they might be able to develop a way to certify Ellensburg blue agates and that would be amazing.
For anyone wishing to obtain a piece of this rare blue agate I know of two trusted sources. Robert Langford from Langford Jewelry and Lapidary carries both finished, calibrated cabochons and jewelry he has set with his stones. He can be found on Facebook and he posts frequently on the Rare Ellensburg Blue Agate Facebook group page. His website is Langford Jewelers. A second source, Carlson Brothers Jewelers, has by far the largest inventory of Ellensburg blue agate cabochons and custom jewelry available anywhere. They can be reached via their website Carlson Brothers Jewelery.