Oregon may not be the first state a rock hound thinks about when looking for unique gemstones, but it certainly should be. Oregon has a plethora of gold and gemstones that are bountiful especially stemming from alluvial deposits. Alluvial deposits are deposits that derive from rivers. Water often relocates gemstones from the primary source, brought to the surface from a volcanic eruption for example, to a secondary source that is more accessible to humans. If you are interested in Oregon rockhounding or just learning more about the bounty Oregon brings, read on!
Opal
Most would agree that Oregon opal is the prettiest of all the Oregon found gemstones. Often primarily white with some elusive play of color, the phenomenon associated with opals. Opals are formed from water carrying a mineral called silica that seeps into volcanic lava. Lava has air bubbles that, as they cool, become receptacles for the liquid deposits. Rhyolite thunder eggs are the primary form you can crack into to locate opals. One of the best locations is Opal Butte in Morrow County in northeastern Oregon. Knowing the statistics for finding gem quality opal is important because only 10% of geodes in Opal Butte contain opal and only 1% contain gem quality opal with play of color. So, in other words…rare!
Sunstone
Sunstone is Oregon’s state gemstone. Sunstone is a feldspar crystal you can find stemming from volcanic lava flows in the south-central region of Oregon. The nicest sunstone is orange in color with a phenomenon called schiller. Copper particles bring out the orange from the more common orangey-brown color. The more orange, the more schiller effects too as it is defined by light reflection caused by millions of microscopic copper particles suspended in the crystal. Highly prized sunstones are an orangey-red color. Thankfully, Oregon sunstone is not known to have any treatments to make it look nicer.
Obsidian
Obsidian is volcanic glass, often black in color but comes in other colors as well. Considering how many volcanoes there are in the Cascades, means Oregon has a lot of natural obsidian. While obsidian is considered a rock versus a mineral, I’ve still included it in this gemstone article because it can be fashioned into carvings, cabochons, and beads. The most prolific area to find obsidian is the Glass Buttes area in Lake County, in south-central Oregon.
Quartz
The gemstones found closest to home come from the quartz family. The Willamette Valley has an excess of thunder egg-filled agate, jasper, chalcedony. Most rock hounds readily go to gravel bars of the Willamette River and its tributaries to find the various varieties of quartz. One of the most prized agates is called Holley Blue agate, a lavender colored agate specific to the Sweet Home area of Linn County. Unfortunately, Holley Blue agate does not have a public mine for rock hounding. While I won’t go into specific varieties, as there are many, take a rock hammer with you to break open the thunder eggs. Other tools will be needed to sift through the gravel to look for the variety of color this family of quartz contains.
Petrified Wood
Petrified wood, also known as fossilized wood, is fossilized remnants of ancient trees from the Paleocene Era. “The petrification process involves the gradual cellular replacement of decayed organic material by quartz crystals. Ancient trees were washed into rivers or lakes, buried in sediments with the presence of volcanic ash in the oxygen-free environment. The groundwater dissolved silica from the ash. The porous wood structure absorbed the silica-rich water, and over time, the wood tissue was dissolved and replaced with minerals (oregondiscovery.com/petrified-wood).” You can find petrified wood in gravel bars of river, lakes, and streams.
Come visit our Oregon case to see representations of opal, Holley Blue agate, and sunstone both loose and set into jewelry. As always, our sales associates can help you create something that you will treasure whether your stay in Oregon is brief or lifelong. Either way, you will enjoy wearing something made close to home with gemstones found close to home!
Resources
A List of Minerals and Gemstones Found in Oregon by Rock Seeker; https://www.rockseeker.com/minerals-found-in-oregon/; found on January 5, 2022.
Opals in Oregon
by GeologyIn; https://www.geologyin.com/2017/06/where-to-find-opals-in-oregon.html; found on January 5, 2022.
Petrified Wood: Where to find, how to spot?; https://oregondiscovery.com/petrified-wood; found on January 7, 2022.
Rockhounding Oregon: A guide to the states best rockhounding sites
by Lars Johnson (2014); Morris Book Publishing, LLC.
Schiller/Oregon Sunstone
by Jeff Graham; https://www.gemsociety.org/article/schilleroregon-sunstone/; found on January 5, 2022.