CoachA chert is a hard, dense sedimentary rock of microcrystalline quartz, formed in most cases from biogenic opal that dissolved and recrystallised after burial; it occurs as beds, often from siliceous oozes, or as nodules, of which flint, in chalk, is the best known.
বইগুলো এখনো বাংলা ভাষায় পাওয়া যায় না — ইংরেজি সংস্করণ দেখানো হচ্ছে।
Earth and Space Sciences · পরিভাষা