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.

Agate is a type of chalcedony, usually at least slightly translucent and banded or with inclusions. It forms in concentric layers in a wide variety of colors and textures. Each individual agate forms by filling a cavity in host rock. Agate has a hardness of about 7 on the Moh's scale. The name is derived from its occurrence at the Achates River in southwestern Sicily.

Metaphysical Properties: Dendrite Agate is said to assist one in overcoming the sources of guilt, resentment, envy, shame, blame, and other self-destructive emotions. It can help one become more loving towards themselves and others.

In many traditions agate is believed to cure the stings of scorpions and the bites of snakes, soothe the mind, prevent contagion, quiet thunder and lightning, secure the favor of the powerful, and bring victory over enemies.

OakRocks has been in the rock and mineral business for 30 years. We are a great source for Montana Agate and carry a selection of Montana Agate cabochons.