VESUVIANITE - IDOCRASE, SIERRA DE LOS CRUZ, COHULIA, MEXICO (small cabinet)

Vesuvianite, Ca₁₀(Mg, Fe)₂Al₄(SiO₄)₅(Si₂O₇)₂(OH,F)_4, commonly referred to as idocrase, is a silicate mineral that can appear in shades of green, brown, yellow, or blue. This mineral typically forms tetragonal crystals within skarn deposits and limestones that have undergone contact metamorphism. Its name originates from its discovery near Mount Vesuvius, where it was found in lava inclusions. Some of the more aesthetically pleasing crystals are fashioned into gemstones, with notable localities for high-quality specimens including Mount Vesuvius and the Ala Valley in Piedmont.

With a specific gravity of 3.4 and a Mohs hardness of 6.5, vesuvianite was named by Abraham Gottlob Werner in 1795 due to the presence of fine brown crystals at Vesuvius, particularly in the limestone blocks of Monte Somma. The mineral has also been known by various names, including "idocrase," a term introduced by René Just Haüy in 1796, which remains widely used today.