University of Washington Office of News and Information
newsweb@u.washington.edu
Modified: November 20, 2007
newsweb@u.washington.edu
Modified: November 20, 2007
The fall 2002 issue of Northwest Science & Technology, now on newsstands (see list of outlets at end of story), includes articles, briefs and insight pieces including the following story. Published three times a year by the University of Washington, the magazine features work by researchers in Washington, Oregon, Idaho, Montana, Alaska and British Columbia.
It's raining lightly in the Monroe, Wash. parking lot. Ed Lehmann, "Wagonmaster" and trip leader for Washington State Mineral Council, and Bob O'Brien, from the Marysville Rock and Gem Club, give the word to "move out," and nine adults, six kids, and three dogs pile eagerly into pickups and sport utility vehicles.
The Mineral Council is scouting for agate-its first rock-hound excursion for 2002-and the excitement is palpable. With Lehmann in front and O'Brien shepherding the rear, the group swings single-file onto the back roads of Snohomish County in Western Washington.
Rain continues to fall. Forest and farms float by, cocooned in mist. Lehmann's truck turns onto a dirt road and begins a slow climb. The others follow. A mile later, he pulls into a flat turn-around that butts against a 20-foot rock wall, half buried in a fan of loose boulders and smaller rocks.
Kids in hats and raincoats and dogs trailing leashes immediately fill the area, scrambling over each other and everything else. Lehmann strides from his truck in waterproof pants and jacket, carrying a five-foot solid metal pole with a beveled head. "I always tell people, don't expect a lot. But some of the stuff you're going to get will be nice gemmy material." He grins and leads the group up the road towards an old quarry with agate veins purportedly 6 to 8 inches wide. No one notices the rain.
Thanks to one hundred million years of tectonic plate activity, colorful minerals pattern the surface of Washington, Idaho, Oregon, Montana, and British Columbia like a bejeweled crazy quilt.
Dazzling amethyst crystals line the caves near Washington's Snoqualmie Pass; 35-million-year-old thundereggs languish in the Oregon desert; lime-green fluorite crystals stud mountain veins in British Columbia; fire opals glow in Idaho's Centennial Mountains; and sapphires wash into Montana gravel bars like so many chips of colored glass.
"We're on an active plate margin. That's why we have a variety of collectable minerals," University of Washington geology graduate student Jeff Schwartz tells NWS&T. "You compare us to someplace like Florida: they're adjacent to a passive plate margin where not much is happening. We have subduction, and we have the magmatic and volcanic activity caused by subduction."
The powerful geologic activity that turned the Pacific Northwest into a natural treasure chest began somewhere between 140 and 65 million years ago. During the Cretaceous Period, the earth's crust separated into great landmasses known as tectonic plates. Eventually the Pacific Plate (under the Pacific Ocean) and the North American Plate (holding the continent) made slow but violent contact along a zone that is near the border of Idaho with Oregon and Washington. The lower part of the Pacific Plate was finally "subducted," or forced beneath the North American Plate, shearing and melting rock forty miles below the surface.
Some molten rock erupted through faults and fissures as lava, cooling quickly on the surface into fine-grained basalt. But greater volumes of the fiery magma lay trapped underground, cooling slowly into masses of rock: "batholiths" with areas greater than 40 square miles. Over time, chemical elements precipitated out of the gases and hydrothermal solutions, segregating into mineral compounds and accumulating in cracks and edges-fractured places that became the pockets and veins where many Northwest gems formed.
Relentless plate movement continued, kneading the continental crust like bread dough, folding, pressing, and changing portions of existing stone into metamorphic rock with new conditions for varied gemstone growth. The region's diverse underground environments were eventually lifted into mountain ranges, carrying such brilliants as beryl, carnelian, garnet, quartz crystal, sapphire, topaz, and tourmaline with them.
"The reason we have an incredible variety of gems is because the Pacific Northwest has an example of almost every kind of geology that exists in the world," says Eric Cheney, a UW professor of earth and space sciences. As evidence, he points to the 1990 discovery of diamonds in kimberlite pipes in Canada. These carrot-shaped "blow holes" that shoot diamonds up from the earth's depths are formations usually associated with South African diamond mining.
Arthur Soregaroli, Canadian geologist and mining explorations specialist, says the discovery has changed the way the world thinks about diamonds. "Canada is fast becoming a major producer of gem-quality diamonds-some of the best in the world that bring in top prices."
It was not diamonds but quartz crystal that awed the ancient Greeks, who called it "krustallos"-ice formed by the gods. Discovering crystals inside Northwest rocks is equally thrilling to contemporary collectors like Jeff Schwartz.
"You dig through these crummy gray-black basalts [fine-grained volcanic rock] then all of a sudden you hit this snow-white pocket. The contrast! It blows your mind how you can have this dirty rock and inside of it is a pocket of perfectly pristine, gemmy crystals that are snow white. It's the most beautiful sight when you break into a pocket. There's nothing like it!"
Quartz is an abundant Pacific Northwest crystal that appears in coarse, crystalline varieties, such as translucent amethyst and rose quartz, and in more opaque, microcrystalline varieties such as jasper and agate. Searching for agate is particularly popular because, when cut and polished, this form of quartz offers up rich colors and graceful patterns. Oregon's famous thundereggs are actually created from an agate "filling" that forms in the cooled gas bubbles burped up by lava-nodules varying in size from a quarter of an inch to about five feet in diameter. Slicing a thunder egg in half can expose a fascinating mosaic of agate outlined by a band of star-shaped, milky quartz.
"Most people grow up, especially in the cities, not ever seeing what Mother Nature provides," explains Glen Saurdiff, gemologist and owner of Jerry's Rock and Gem shop in Kent, Wash. "And once they realize that quartz crystals grow that way-someone didn't make them-they're converted to collectors."
The Northwest's mineral diversity offers unique opportunities for collectors who know how to access established dig sites. Highway 20 snakes through the Okanogan National Forest and over Washington Pass. Road construction in the high mountain terrain near the pass summit has exposed portions of the Golden Horn batholith of the Eocene period, creating a famous collection site for rare minerals. Members of the Pacific Northwest Chapter of Friends of Mineralogy routinely collect specimens in the granite outcrops and road fill just below the summit and east for a few miles to the Silver Star Mountain parking area. Many specimens are small-so small that collectors "micromount" each mineral and display them, using a microscope for viewing.
Saurdiff says people who search for gems tend to label themselves either as rock hound or mineral collector. But since minerals are the basic building blocks of rock, he sees the distinction as artificial; both are technically mineral collectors with different goals. The rock hounds seem to have an interest in turning gems into art objects, Saurdiff notes, while mineral collectors are primarily interested in specimens for their own sake, no matter how small.
For the beginner, purchasing a map and striking out alone into mountainous or dry terrain can be frustrating and sometimes even dangerous. Bob Jackson, geologist and owner of both the Spruce Claim in Washington and the Rock Candy Mine in British Columbia recommends joining a club. "Most people don't know where to go or what to do or look for-that's why joining a club is such a good idea. The camaraderie of being with other people who like to do it is important also. The clubs are going to be best at knowing what's hot right now."
Accessing dig sites has become increasingly complex. Umbrella organizations like Washington State Mineral Council (WSMC) promote good will among clubs, private landowners, and state and federal land agencies, in order to ensure continued site access for collectors.
The WSMC sponsors eight months of weekend trips each year within British Columbia and Washington. The fee is a nominal 50 cents per person per trip day to cover insurance. Excursions take both beginning and long-time collectors to a variety of reliable, legal, and conservation-friendly digging sites.
WSMC also maintains free claims or leases around the state that are open to the public: Walker Valley in Skagit County yields blue agate, high-quality geodes (round rocks filled with calcites and crystals), and amethyst. Red Top Mountain outside Cle Elum is a source of Ellensburg Blue agate; and the Cascade River claim near Marblemount has soapstone.
Prospectors looking for a sure thing, or in search of bigger and better specimens, often pay to dig at private claims. The Spruce Claim in the Snoqualmie batholith is a fee-dig site that requires high spirits and an arduous hike but guarantees beautiful crystals.
Exploring and laying claim to the Spruce one summer, while still a geology graduate student, gave Jackson one of the finest pyrite and quartz sources in America.
Jackson says he has been fortunate so far to supply museum-quality quartz specimens from the site to every major museum in the world. "I don't know if it's a gene or not, but there's something in our makeup that either makes us a collector or not. I know so many people who are not only mineral collectors, but they collect microscopes, antiques, plants, whatever. Then there are people who collect nothing. I don't understand those people, but I think you either have it or you don't."
ABOUT THE AUTHOR: Judith Calman has a background in health sciences and works in cancer research. She has studied science writing at the University of Washington
Need copies of Northwest Science & Technology? Distribution outlets:
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Eastside Daily Planet
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Port Angeles:
Port Book & News
Pullman:
Student Book Corporation (WSU)