Biogenic substance
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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.