Clayton developed the GGI as part of a method to estimate the maturity of this substance by examining how much gas is emitted by it.
Clayton developed the GGI as part of a method to estimate the maturity of this substance by examining how much gas is emitted by it. Tissot classified this substance into three different types, each with different Arrhenius activation parameters, based on the ratio of this substance's constituent elements and its subsequent maturation track on a van Krevelen diagram. Type IV of this substance is made from polycyclic aromatic hydrocarbons, while Type II examples of this component of source rocks include resinite and sporinite. Crum Brown coined the name for this material, whose sapropelic type is often found in underwater rocks. When Types I and II of this substance are heated, it produces bitumen. For 10 points, name this waxy, organic component of oil shale that is insoluble in most organic solvents, and which is a precursor to many fossil fuels. 
Clayton developed the GGI as part of a method to estimate the maturity of this substance by examining how much gas is emitted by it.
kerogen [prompt on "(oil) shale"]