A dilute sodium hydroxide technique for radiolarian extraction from cherts

Area of Science:

• Paleontology
• Geochemistry
• Materials Science

Background:

• Radiolarians are crucial microfossils for determining geological ages and understanding Earth's history.
• Traditional extraction methods utilize hydrofluoric acid (HF), which poses significant environmental and human health risks and is subject to strict regulations.

Purpose of the Study:

• To develop and validate a safer, more accessible alternative to HF for extracting radiolarian fossils from cherts.
• To compare the efficacy and fossil preservation quality of the new method with the conventional HF technique.

Main Methods:

• Dissolving chert samples using a low-concentration sodium hydroxide (NaOH) solution (1 mol/L).
• Investigating the temperature-dependent dissolution rate of chert in NaOH.
• Comparing the preservation of radiolarian fossils extracted via NaOH with those extracted via HF.

Main Results:

• Successful extraction of radiolarian fossils was achieved using 1 mol/L NaOH at 100°C.
• The NaOH method demonstrated superior preservation of radiolarian fossil details compared to the HF method.
• Chert dissolution in NaOH was found to be temperature-dependent, with limited dissolution below 80°C.

Conclusions:

• A 1 mol/L NaOH solution provides a viable, less hazardous alternative to HF for radiolarian fossil extraction.
• This NaOH method offers improved fossil preservation and is safer for researchers and the environment.
• The technique is recommended for broad application in paleontology research and education, especially where HF use is restricted.