Polka-dot agate - at the time it formed it was a tube or fissure that at the time was still beneath the Pacific Ocean. When the Columbia River Basalt flows and the rise of the Cascade Mountain range caused the tubes to come into contact with the ocean and form the agate. The composition is silica from the volcanoes combined with iron and limonite. The red dots are hematite. It was long used by indigenous people for weapons and tools because it flints well and is very hard.

Hand-cut stone. Measures 2" x 1 3/4"