What analysis method is required for all amphiboles that would cause above 70 s/mm2?

The correct method for analyzing amphibole asbestos that would cause results above 70 s/mm² is Energy Dispersive X-ray Analysis (EDX or EDS). This technique is particularly effective for identifying and quantifying the elemental composition of materials at the microscale. When dealing with amphiboles, which are a group of minerals associated with asbestos, EDX provides a clear advantage in distinguishing these materials based on their specific elemental signatures.

Amphibole asbestos types, such as amosite or crocidolite, require precise identification due to their health risks and regulations surrounding them. EDX allows technicians to perform detailed examinations of samples, helping to ensure compliance with safety standards and adequate risk assessment.

The other methods listed, while useful in various contexts for material analysis, do not have the same specificity and sensitivity for identifying amphibole asbestos in the same manner as EDX. Gas chromatography is typically used for analyzing organic compounds, infrared spectroscopy can identify functional groups but may not accurately identify certain minerals, and mass spectrometry is more complex and not primarily used for direct analysis of fibrous minerals like amphiboles. Thus, EDX stands out as the required analysis method in such cases.