Final answer:
Prussian blue is the histological stain used to visualize iron, producing a blue or blue-black color in the presence of iron deposits in tissues.
Step-by-step explanation:
The histological stain used to visualize iron is Prussian blue. Prussian blue reacts with iron in tissues, resulting in a blue or blue-black staining that enables the identification and visualization of iron deposits. This is particularly useful in cases of iron-overload diseases or to detect the presence of hemosiderin, an iron storage complex. Other histological stains, while useful for various applications, are not specifically used for visualizing iron. For example, Methylene blue and crystal violet are basic stains that positively charge to bind bacterial cells, while safranin and eosin are used as counterstains in different staining protocols like Gram staining and Wright-Giemsa staining.