What distinguishes rhodolite garnet from other types of garnets?

The defining characteristic of rhodolite garnet is indeed its composition, which is a solid solution mixture primarily of pyrope and almandine garnets. This unique blend results in a distinct range of colors and properties that set rhodolite apart from other garnets. Rhodolite garnet typically exhibits a purplish-red to pink hue, making it visually differentiated from its counterparts, especially when considering garnets like almandine, which tends to be darker red, or pyrope, which can also exhibit a more vivid red without the hint of violet.

The other options, while they may describe features of various garnets, do not accurately capture the essence of what makes rhodolite garnet unique. For instance, bright green color is not associated with rhodolite but rather with other garnets such as tsavorite, while intense red hues are more characteristic of other specific garnet varieties like almandine. An iridescent glow is also not a typical feature of rhodolite garnet but can be seen in different gem types. Thus, the correct identification of rhodolite garnet through its composition highlights its distinctiveness within the garnet family.