Altarite

Altarite is a rare, naturally occurring mineral that was first discovered in the late 19th century. It is named after the altar of the Temple of Apollo in Delphi, Greece, where the mineral was initially found. Altarite is a member of the pyroxene group of minerals and is characterized by its dark green to black color, metallic luster, and prismatic crystal habit. It typically forms in igneous rocks, such as gabbros and diorites, and can also be found in metamorphic rocks.

The chemical composition of altarite is complex, with the general formula (Ca,Na)(Mg,Fe,Al)(Si,Al)2O6. This formula indicates that altarite is a calcium, sodium, magnesium, iron, and aluminum silicate. The mineral's structure is characterized by single chains of silica tetrahedra, which are linked by calcium and sodium cations. This structure gives altarite its distinctive prismatic crystals and its hardness, which is typically around 5.5 to 6 on the Mohs scale.

Altarite is not commonly used in industry or jewelry due to its rarity and the difficulty of mining it. However, it is sometimes collected by mineral enthusiasts for its aesthetic appeal. The mineral's rarity and unique properties make it an interesting subject for study in the fields of geology and mineralogy.