Columbia River Stone Mortar that measures 6 1/2" long by 5" wide. A high grade, mid size mortar

Columbia River Stone Mortar that measures 6 1/2" long by 5" wide. A high grade mid size mortar with an unusual and unique rectangular form. Worn smooth to the touch with a deep bowl area. Very symmetrical and well made object. From the Bill Peterson collection. Bill was a member of the O. A. S.