quartzite pebbles from alluvial terraces

quartzite pebbles alluvial terraces flakes stone closeup geology lithic flints sharp carse rocks fragments clay vessel earthware washbowl selective focus natural light minerals vegas altas del guadiana orellana la vieja badajoz extremadura grainy glassy sandpaperlike surface hard metamorphic rock hematite long format orange crushed silica silicon nature rough loads pieces texture roughly geomorphology roofing flooring countertops resistant