What inclusions are notably found in pyrope, spessartine, and almandine garnets?

The choice of horsetail inclusions as being notably found in pyrope, spessartine, and almandine garnets is correct due to the specific characteristics of these garnet varieties. Horsetail inclusions are a distinctive type of healing feature within gemstones that resemble the configuration and branching of a horse's tail. These inclusions often appear as thin, thread-like structures that can create a distinctive pattern within the garnet.

This type of inclusion can occur during the formation of the garnet, often resulting from the crystalline structure undergoing changes like stress or temperature fluctuations. Such inclusions can be caused by the presence of other minerals or by environmental factors during the crystal growth process.

In contrast, feather inclusions, which appear as thin lines or fractures, are more commonly associated with other types of gemstones and may not be specifically highlighted in garnets. Needle inclusions, while resembling fine, elongated crystals, are less characteristic of garnets. Gas inclusions generally occur in certain types of gems, particularly those that form in volcanic environments, but they are not a notable feature of garnets like pyrope, spessartine, and almandine.

Thus, horsetail inclusions are a defining feature for these garnets, making them