Agate, Montana, Pairs, Cabochons, 100 Gram Lot, Assorted Shapes & Sizes
Agate, Montana, Natural, Pairs, Cabochons, 100 Gram Lot Assorted Shapes & Sizes.
Size range is 10mm to 20mm.
This image is of a similar assortment of 100 grams of Montana Agate.
Montana Agate could also be known as the Yellowstone Agate since its origin was along the Yellowstone Park area. Montana Agate is the term given to the stunning chalcedony that was found in the alluvial deposits of the Yellowstone River. Alluvium is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain.
The background matrix of Montana Agate ranges from nearly clear, through milky grey blue to white. Some Montana Agates, appear to have originated from wood that became buried by ash and fossilized after the volcanic activity. One of the most attractive features of Montana Agate is the colored inclusions, which are made up of different elements (such as iron and manganese). These inclusions form when mineral-laden water is “wicked” into the rock through cracks or fractures and the mineral content of the water is deposited within the rock.
It's probably safe to say that all Montana Agate has been transported many miles from its original location. They are found over a broad area along the Yellowstone River Valley and adjacent plateau areas from Emigrant MT to the North Dakota border. Rough Montana Agate rough often resembles a potato because they develop a white crust.
Montana Agate and Sapphire are the two State gemstones of the State of Montana.
This is a natural stone that has had no treatment other than cutting and polishing.