Ellensburg blue agate unique to Kittitas County

Abigail Duchow, Staff Reporter

Ellensburg blue agate is a gemstone that is unique in that it is only found in Kittitas County. It was discovered in 1905 by the first mayor of Ellensburg, Austin Miers. It has since become a staple of Ellensburg, nominee for Washington’s state gem and sought after by many people.

Ellensburg blue is the only agate considered to be a semi-precious gem. It can only be found in northwest Kittitas County, particularly around Green Canyon and Reecer Creek Roads.

Angela Halfpenny is an Engineering Technician in the CWU Geology Department. She has been researching Ellensburg blues. Specifically, she has been researching what makes Ellensburg blues unique from other blue agates and how they can be properly distinguished from others.

“The reason it’s more important than the other blues, like a Holly blue, Turkish Blue, Mojave Blue or a Blue Lace, is the fact that because it’s rarer, it’s worth a lot more money per gram. So, that’s why some people are very interested in it,” said Halfpenny.

Blue gold

Sadie Thayer has been the director of the Kittitas County Historical Museum since 2010. She said the museum has had its Ellensburg blue exhibit since it opened in 1961.

Riel Hanson

Thayer said that Ellensburg blues are mainly sold to jewelers to be cut and made into jewelry. She said there is another market for Ellensburg blues with people who collect them. The ones that aren’t sold to jewelers are usually raw and aren’t gemstone quality.

A problem that arises from Ellensburg blues being worth so much is Ellensburg blue fraud. Some people have taken stones that look similar to Ellensburg blue, cut it in the shape that Ellensburg blue is usually cut in, and try to sell it for as much as an Ellensburg blue would be sold for. Ellensburg blues can be sold for as much as $250 per karat.

“[Ellensburg blue fraud] is common, folks can pass off blue lace agate, which has a similar property and similar look to Ellensburg blue, and claim it as Ellensburg blue,” Thayer said.

While Ellensburg blue has always been rare, over time it has gotten even harder to find. Thayer described how in the 1970s there was a major push called the “rock days.” During that time the interest in Ellensburg blues grew even more. The Ellensburg blue was celebrated among rock hunters, and promoted more ever since. Since this time of immense popularity, it has become harder to find Ellensburg blues.


Thayer talked about how Ellensburg blues have had a vibrant history. She described how the first mayor of Ellensburg, Austin Miers, sent two “beautiful pieces” of Ellensburg blue to a jeweler in Seattle to be made into rings. 

Thayer also talked about J.N.O. Thompson, a man who had a jewelry store in Ellensburg from 1913 to the 1940s. She said that Thomspson’s “go-to stone” was the Ellensburg blue, which was a factor in popularizing the Ellensburg blue. The jeweler’s son, John Prentiss Thompson, became a geologist and wrote a book about Ellensburg blues.

According to History Link, a website that contains history about Washington state, Ellensburg blues were shown to John Prentiss Thompson by local Native American tribes. The tribes used Ellensburg blues to make arrowheads as well as to trade with. 

The Ellensburg blues even caught the attention of Tiffany and Co in the late 20s. According to Thayer, a Tiffany and Co salesman came to Ellensburg, saw the Ellensburg blue, and promoted all over America. 

State Gem

Thayer is one of the people that testified for House Bill 2757, a bill calling for Ellensburg blue to be named the official gem of the state of Washington. The current state gem, petrified wood, would be renamed as the official vegetative fossil of the state of Washington. 

The bill passed in the house with 91 yeas and 7 nays, and was passed to the senate. However, the senate never got to hear the bill due to a missed deadline. 

“We had critical dates that we had to meet, and unfortunately we didn’t meet one of those, and that’s why it had to be stalled,” Thayer said.

The bill’s next opportunity to be brought back to its current status of in committee in the senate will be Jan. 2021, the next legislative cycle. 

“It gives us a chance and an opportunity to cultivate support and get the word out.” Thayer said of the wait, “After election season is over and we see who our state representatives and senators are, we can start promoting to them and saying ‘here’s a bill you should be aware of, and here’s why it’s important to say yes.’”


Angela Halfpenny described how Ellensburg blues are formed, and how they got to Ellensburg. According to Halfpenny, Ellensburg blue is chemically distinct from other blue agates due to variations in trace element chemical signatures and crystallography.

Halfpenny said Ellensburg blues are a vein-hosted mineralization. They form when fluid pressurizes deep in the earth and cracks up a solid chunk of basalt. The fluid goes up the crack, mineralizes, and grows out from the walls and into the middle of the crack.

“We theorize that there was a river that brought the Ellensburg Blues from up behind First Creek, where they were initially formed.” Halfpenny said, “A whole heap of rock has been eroded off the top of First Creek, so that’s where [Ellensburg Blues] separated out, and that’s what got deposited and people are now finding in their gardens and things like that if you live up Reecer Creek Road or around Green Canyon.”