Biggs jasper is a variety of the mineral jasper. It is a “picture jasper” – a jasper that exhibits particular patterns and colors – and is used as an opaque gemstone. It exhibits intricate, shell- or layer-like patterns in shades of brown ranging from beige to dark brown.
The stone was first discovered around 1960 near Biggs Junction, Oregon, and is found in the basalt deposits of the American Pacific Northwest. Biggs jasper was formed as mud from volcanic ash was deposited on basalt terrain, and subsequently heated and compressed through volcanic activity. Because of this sedimentary origin, it is relatively rare, and is valued as a gemstone.