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Montana Agate
Montana Agate comes from near the Yellowstone River in Montana.
The vein actually runs from the Yellowstone National Park in Wyoming to North Dakota. Montana Agate is one of the alluvial agates, it is not found in-site, but in the Flaxville gravel deposits scattered over a huge area encompassing thousands of square miles. The area between Custer and Sidney is rich in agates. The best agate hunting is done by boat in the late fall when the water level is low.
Montana Agate is believed to be 50 million years old. The agate originally was formed in the Yellowstone National Park area of Wyoming as a result of volcanic activity. Montana Agate is typically clear to slightly yellow with red, brown, or black spots or dendrites. The red color is the result of iron oxide, the black is the result of manganese oxide. It is considered a moss agate or dendrite agate.
Artifacts discovered show the agate was used by Native Americans to make arrowheads. It is believed it was first cut and polished in 1914.
Montana Agate has been the state of Montana's official state gemstone (along with Montana Sapphire) since 1969.
Montana Agate is considered a moss agate, as most of it's inclusions are mossy looking, but it can also be a banded agate or polka dot agate!
OakRocks has been in the rock and mineral business for over 40 years.
We are a great source for Montana Agate and carry a selection of Montana Agate polished and unpolished rocks and slabs.