“Iris” Agate slab-
Paulina Agate limb cast with rare Iris effect –
South Fork Crooked River.
Paulina, near Prineville, Oregon.
Eocene epoch…
6″ across.
“Iris Agate” is a name used for a finely-banded agate that produces a spectacular display of color when it is cut properly and illuminated from a direction that sends light through its very thin bands. The name “iris agate” is used because one meaning of the word “iris” is “a rainbow-like display of colors.”
South Fork Crooked River or “Paulina” Limb Casts,are found at the South Fork Crooked River. The Crooked River is a tributary of the Deschutes River in the U.S. state of Oregon. The river properly begins at the confluence of two tributaries, South Fork Crooked River and Beaver Creek. The river is part of the Columbia River basin, being a tributary of the Deschutes River, which is tributary to the Columbia River. Here are extensive agate beds with many great limb casts. Only rarely is wood structure preserved. The volcanic rock is Miocene in age (Colombia River Basalts).
