Lakeview, Oregon: Sunstone (Feldspar) Gem Mines
The arid south-central portion of Oregon is a classic volcanic region. There the relatively young rock consists of dark basalts, andesites, rhyolites, ash and cinders. Millions of years ago a magma chamber several miles below the surface supported the correct geochemical conditions for the growth of labradorite, a calcium-rich plagioclase feldspar. ... http://www.mtlilygems.com/mineinfo/plshinfo.html
The Yellowstone hot pocket?
I'm not sure. If you look at a map of Idaho you an see a long volcanic scar across the southern part of the state called the Snake River Plain. It's a huge jumble of basaltic lava flows and the location of the other-worldly Craters of the Moon National Monument. Current theory suggests it's the result of the American plate moving westward over the Yellowstone Hot Spot (which remains stationary.) It's a process that seems to be continuing.
Oregon and the West Coast in general have seen plenty of volcanic action and it's going to continue. I have a hunch the sunstone region is more likely the result of volcanism related to subduction of the Pacific Plate under the American plate. Subducted rock forms magma chambers resulting in active volcanoes like the Three Sisters at Bend, Mt. St. Helen's, etc., extending south to Lassen and Shasta in California and all the way to the tip of Chile.
We're lucky to live in a time when those Ring of Fire volcanoes are relatively inactive. Think of what it would have been like if we'd been around when the Columbia Plateau Flood Basalts were forming! Columbia Plateau