The matrix is light brownish-green to greenish-brown in plain polarized light. The clay minerals had changed their optical properties and are strongly vitrified as a result of firing at the temperature close to 800C. The temper is olivine-iddingsite sand (up to 85% of total) – large (up to 0.3 mm) rounded reddish-brown to dark brown grains, sometimes containing relict olivine nucleus. They compose about 15% of the total volume of the sherd. Also appear: olivine not altered into iddingsite - small angular to rounded grains; plagioclase - small grains, some of them with character twinning; schist - single rounded grains. Rare are: chalk balls, chlorite that is also secondary altering of olivine (large aggregates, golden-brown in PPL), amphibole - angular grains.
Some hollows – from tiny cracks to large round bubbles.