Kerogen containing mostly decomposed organic matter also known as charcoal is what type of kerogen?

• A. Type IV
• B. Type I
• C. Type II
• D. Type III

Answer: (D)

Charcoal-like material in kerogen points to inertinite, an oxidized, highly carbon-rich form of organic matter. In kerogen classification, this inertinite-rich material defines Type IV kerogen, which has little to no hydrocarbon generation potential. While Type I and II kerogens are hydrogen-rich and oil-prone, and Type III is more gas-prone from terrestrial plant material, the presence of mostly decomposed, charcoal-like matter means the kerogen is largely inert—hence Type IV.