... metamorphic schist (For hard, low abrasive formations)2. Gneiss, Diorite, Basalt (For hard and abrasive formations)3. Quartz, Granite (For ... water well, oil field, construction, geothermal, directional boring, and underground foundation work Formation sticky, soft, medium hard, hard ... formation Bearing rubber seal or metal seal Packing wooden box, steel box, or as your requirements Payment Term T/T ...