"Kerogen (Greek \u03BA\u03B7\u03C1\u03CC\u03C2 \"wax\" and -gen, \u03B3\u03AD\u03BD\u03B5\u03C3\u03B7 \"birth\") is a mixture of organic chemical compounds that make up a portion of the organic matter in sedimentary rocks. It is insoluble in normal organic solvents because of the high molecular weight (upwards of 1,000 daltons or 1000 Da; 1Da= 1 atomic mass unit) of its component compounds. The soluble portion is known as bitumen. When heated to the right temperatures in the Earth's crust, (oil window ca. 50\u2013150 \u00B0C, gas window ca."@en .