black colored rough messy dirty blackboard or writing slate with scuff marks, textured effect grunge vector horizontal background that is plain blank and empty - geology 幅插畫檔、美工圖案、卡通及圖標
fracking or hydraulic fracturing flat vector illustration with fracking gas in rich ground shale with spanish text - geology 幅插畫檔、美工圖案、卡通及圖標
a naphtha source ,industrial oil belt, better known as black city, was established near baku - geology 幅插畫檔、美工圖案、卡通及圖標
