A biogenic substance is a substance produced by life processes. It may be either constituents, or secretions, of plants or animals.

Examples

• Coal and oil are examples of constituents which have undergone changes over geologic time periods.
• Chalk, and limestone are examples of secretions (marine animal shells) which are of geologic age.
• Cotton and wood is are biogenic constituents of contemporary origin.
• Pearls, silk and ambergris are examples of secretions of contemporary origin.