Montana Agate Rock slab 004
Montana agate has been a long time favorite of the lapidary enthusiast. Found in the alluvial gravels of the Yellowstone River in eastern Montana it has been collected and worked as a semiprecious stone for nearly a century. Noted for its clarity as well as its characteristic isolated black, and occasionally bright red dendrites, it makes excellent cabbing material. The majority of Montana agate pieces show a well-defined fortification pattern of black and brown as well as bright red/orange. There are also variations of filament and tube patterns and a small percentage display an “iris” band in which minute, regularly spaced layers act as a diffusion grating and, like a prism, break light into a rainbow of color. It is a relatively easy material to work with, being quite hard, and takes a brilliant polish.
Origin: Montana, US
Dimensions: 2.75" x 2" and approximately 4.4 mm thick. Weight = 30 g.
Shown wet. Not polished. Flaws are shown as white lines in the final picture frame.
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