তৈলমৰ্দন কৰ্তৈলাক্ত
তৈলযুক্ত বোকাশিল (Assamese)
1. Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general... from wikipedia.org