What type of microscope is used to identify asbestos in bulk samples?

The correct answer is the use of Polarized Light Microscopy (P.L.M.) to identify asbestos in bulk samples. P.L.M. is a specialized technique that utilizes polarized light to examine the optical properties of minerals, making it particularly effective for identifying asbestos fibers. Asbestos has specific optical characteristics that can be differentiated under polarized light, allowing scientists and technicians to distinguish it from other materials in bulk samples.

P.L.M. is a widely accepted method in the field due to its effectiveness, simplicity, and relatively low cost compared to other microscopy techniques. This method can rapidly analyze samples and provide reliable results regarding the presence of asbestos, which is crucial for ensuring safety and compliance with health regulations.

While Electron Microscopy is also used to identify asbestos, it is generally more complex and expensive, primarily used for detailed structural analysis rather than routine identification in bulk samples. Optical Microscopy is a broader term that doesn't specifically address the unique capabilities of polarized light, thus making it less suitable for distinguishing asbestos. Scanning Optical Microscopy may refer to advanced imaging techniques but it is not commonly recognized for asbestos identification specifically.

Thus, P.L.M. stands out as the preferred choice due to its reliability and efficiency in directly identifying asbestos fibers within bulk materials.