Photograph of polarised thin section of stone adze (ISAP 11712) from River Bann Near Coleraine, Co. Derry, from the Ulster Museum (UM WM 3009). Macro-ID - Porcellanite. Micro-ID - Porcellanite II. Petrology - Grey, evenly coarse mottled. Description - Sides - Left is slightly thicker than right, junction of sides with edge and butt is clear, well defined polished facets on both sides. Edge - very minor chipping, close to the sides, but is still fairly sharp, S-shaped in profile. Blade area merges into faces on both faces. Faces - Face 1, damage below the butt, in the upper right portion, leaving the right side facet incomplete, Face 2, large surface flake has been removed, (post-manufacture), from the direction of the butt, Faces 1 and 2, small remnant flake scars on both, close to the sides. Butt - Appears original, Surface slightly irregular, sloping from Face 1 to 2. Core taken from butt. No visible striae. Dimensions (length x width x thickness) - 7.2 cm, 5.2 cm, 2.2 cm, 143g.