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Gems and Minerals in Oregon
Learn more about Oregon's geology


The thunderegg is a structure
created in welded tuff or perlitic rocks

Gems and Minerals in Oregon

Please be aware it is illegal to alter, damage, or destroy an archeological site on any lands, per Oregon Revised Statute 358.920.

The thunderegg is Oregon’s state rock.

Oregon’s state rock can be collected at fee and free sites in central and southeastern Oregon. Unimpressive on the outside, these spherical rocks contain colorful silicic material and, when sliced and polished, make beautiful collector’s items.

For information on places to collect in central Oregon, contact

    Madras Chamber of Commerce, 197 SE 5th St., Madras OR 97741, phone 541-475-2350;

    Prineville Chamber of Commerce, 390 North Fairview, Prineville, OR 97754, phone 541-447-6304,

    In Southeastern Oregon contact the Bureau of Land Management (BLM), 100 Oregon Street, Vale OR 97918, phone (541) 473-3144,

    To find out more about Thunderegg Days (held for five days around the first of June), in Nyssa, contact the Nyssa Chamber of Commerce at   (541) 372-3091.

    More on Thunderegg sites in Oregon

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Oregon Department of Geology and Mineral Industries
800 NE Oregon Street, Suite 965, Portland, OR 97232-2162
(971) 673-1555, FAX (971) 673-1562
email us at DOGAMI