Which type of microscopy is useful for identifying crystals that are double refractive?

The type of microscopy that is particularly useful for identifying double-refracting crystals is polarizing microscopy. This technique utilizes polarized light, which interacts differently with anisotropic materials like crystals. When light passes through these materials, it can split into two rays that travel at different speeds, resulting in double refraction.

In polarizing microscopy, the use of polarizers and analyzers allows for the visualization of these unique optical properties, making it easier to identify various crystalline structures based on their birefringence. This capability is especially crucial in hematology for the evaluation of certain inclusions or crystals within cells, helping to diagnose conditions related to crystal formation.

Other methods, such as compound brightfield microscopy, darkfield microscopy, and phase-contrast microscopy, do not provide the specific optical details needed to effectively observe and differentiate double-refractive crystals due to their design limitations regarding light manipulation and contrast enhancement. Thus, polarizing microscopy is the best choice for this purpose.