Emerald is a variety of which mineral family?

Emerald has priority over beryl as a mineral name. Emerald was known in antiquity and was prized as a gem. In the 1790s, Louis Nicolas Vauquelin, the discoverer of chromium, demonstrated that emerald and beryl were essentially the same chemical compound and that emeralds, sensu strictu, contained chromium.

Nonetheless, emerald continued to be listed as the preferred species name for many decades and emerald finally began to be used as a variety name for beryl by the 1830s. New emerald reports referring to ordinary green or even blue beryl persisted in the amateur literature into the twentieth century. In the latter twentieth century, it was discovered that some emeralds contain more vanadium than chromium.

A green gem variety of beryl, highly sought after as a precious gemstone. The majority of the world's gem-quality emeralds come from the Muzo area of Colombia.

The colour of emerald is caused by trace amounts of a chromophore such as trivalent chromium or trivalent vanadium.