Fossils, Rocks & Minerals - Oregon



Nationally known as a great place for rock hounds, Oregon produces a great variety of types rocks and quartz minerals. The plentiful mineral deposits of the state are supplying the museums, private collections, and shops with colorful and valuable semi-precious gem and cut rock specimens.

Oregon Fossils, Rocks & Minerals

Agate is a translucent or semitransparent a fine-grained cryptocrystalline quartz composed of silicon dioxide SiO2. The tough and attractive mineral has excellent working properties. Read more...

Fossilized Agate - an agatized form of marine life such as clams or snails. Engulfed by lava, all inside of the shell has been replaced with agate and other types of chalcedony.

Jasper is like agate originated from chalcedony (a type of quartz) and features iron oxides, hydroxides and other impurities that create unique color combinations. Read More...



Geode is a hollow rock, often with mineral growth inside. Mostly, filling-materials are quartz crystal but may include opal or zeolite.

Thunderegg is the round nodule-like rock formation, filled with agate, jasper, opal and other minerals. Read more...

Limb Casts or Fossil Wood formed in volcanic ash cavities which before were occupied by wood. The wood structure is either burned out or decayed. Later, minerals from groundwater have been deposited in the cavities.

Limb casts are found in Central Oregon - the Congleton Hollow and Dendrite Butte sites.

Obsidian - a volcanic glass that is classified as an extrusive igneous rock (not a mineral). When basalt cools quickly by contacting with water, mineral crystallization is minimal. Basalt forms into a glassy structure. Obsidians are brittle and mostly black with green, purple, bluish shades viewed on the fractured shiny surface.
The best place to find a variety of iridescent obsidians is the Glass Butte Obsidian in Lake County of Southeastern Oregon.

Opal - a hydrous amorphous (non-crystalline structure) form of silica. Common opal is widely-distributed in Oregon and Nevada. Precious fire opal is rare. In Oregon, the opal deposit has been found in Morrow County, Opal Butte. However, this location is not available to the public.



Opal collecting for fees is available in Northern Nevada: Royal Peacock Opal Mine and Kokopelli Opals Mine.

Petrified wood, also known as Fossilized Wood, is fossilized remains of ancient tree plants from the Paleocene Era. The name "Petrified" came from Greek "petro" that means "stone", literally, "wood turns to stone". Read more...

Sunstone is a transparent or translucent feldspar crystal with a wide variety of colors including clear white, yellow, red, green, and blue. The size of specimens is usually between an inch and two. Read more...





1. Arthur Thomas. "Gemstones: Properties, Identification and Use". 2008.

2. "Oregon Rocks, Fossils Minerals". Josefine County. Oregon Historical Society.

3. Nancy Marie Brown. "How Do Agates Form?". 2001. Penn State University.

4. Dr. H.C.Dake. " The Gem Minerals of Oregon". 1938. Portland, Oregon. Oregon State Department of Geology and Mineral Industries.


3 Comments

  1. I am interested in collecting ores in Oregon for hobby smelting. My preference is for copper ores since the smelting process for copper is relatively easy. Secondarily, I am interested in iron ores (the information you provided concerning rhodonite was very helpful).

    Thank you for the excellent article on rockhounding in Oregon!

    1. I don’t know of any place in Oregon that has copper deposits in mine-able amounts.

      The best states are Arizona, Utah, New Mexico, Nevada and Montana. There is also a little in Idaho.

  2. There are ore deposits in the mountain areas of Cascade Mountains near Upper Lake Chelan. The Holden mine near Lucerne is closed and sealed! There was a full on iron ore, copper and gold operation in Copper Mountain inside. 56 miles of tunnels built to remove mined materials. J.R. Holden scouted and discovered in late 1880s. A Local banker in Lake Chelan loaned him money to work the mine.
    The banker wanted his loan money realized!
    The was sitting on a lot of money! J.R. died in 1919
    leaving the banker who was not a manner owning the mine after paying the Holden family off. The banker spent years trying to sell the mining operations.
    Howesound Mining Company finally purchased the operation.1930s. Howesound built a working town, the mine was called the Holden. There was a family
    housing. development outside of the town called Winston, 100 homes. At one time the mining continued at an area above Copper mountain. It was called Honeymoon Heights.
    Holden had a school, gym, post office, dining hall, and kitchen.
    hotels, dormitories and chalets a barber shop and bowling alley, soda fountain.,hospital
    The town of Holden still exists as it was. Winston was removed by the forest service because of fire danger.. There was a phone system between the mine town and housing. After the mine closed because it eventually began to loose.money!
    The museum was closed recently and moved to a small area. The mine operation was. removed because of danger.
    The Lutheran church eventually purchased the town of Holden for $1.00. It is now owned and responsible for maintaining the town.

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