Examples
- Coal and oil are possible examples of constituents which may 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 are biogenic constituents of contemporary origin.
- Pearls, silk and ambergris are examples of secretions of contemporary origin.
The issue of biogenic vs. non-biogenic carbon has implications for estimating the efficiency and environmental benefits of waste-to-energy incineration processes.
Read more about this topic: Biogenic Substance
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“Histories are more full of examples of the fidelity of dogs than of friends.”
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