piemontite

Piemontite is a rare mineral species that belongs to the inosilicate group. It was first discovered in 1838 in the Piedmontese Alps of Italy, from which it derives its name. Piemontite is a chromium-bearing calcium iron manganese silicate, with the chemical formula Mn2+CaMn4(SiO4)3. It is found in igneous and metamorphic rocks, particularly in those that have undergone high-pressure metamorphism.

Piemontite typically occurs as prismatic or tabular crystals, often in a radial or fibrous pattern. It can also be found in aggregates or as a part of a larger matrix. Its color can vary from bright yellow to dark green, violet, or reddish-brown, depending on the presence of impurities such as vanadium or manganese. The mineral is opaque and tends to have a vitreous to metallic luster.

Piemontite is a relatively rare mineral, especially compared to other manganese silicates like spodumene. It is mainly found in limited locations worldwide, including Italy, the United States (New Hampshire and Oregon), and Australia. Some notable gem-quality piemontite crystals have been discovered in these areas, showcasing the mineral's attractive colors and distinct crystal structures.

Due to its rarity and unique properties, piemontite is of interest to collectors and mineralogists alike. Its distinctive appearance and relatively high hardness make it a valuable addition to any mineral collection. Attention to environmental and geological conditions during its formation has made piemontite a sheltered mineral in geologic and petrographic studies.