Clinohumite

Clinohumite is a rare nesosilicate mineral with the chemical formula (Mg,Fe)9(Si5O16)(OH)2. It belongs to the humite group, which also includes humite, chondrodite, and clinohumite. Clinohumite typically forms in metamorphic rocks, particularly those that have undergone high-temperature and high-pressure conditions, such as skarns and contact metamorphosed limestones. It can also be found in some ultramafic rocks and meteorites.

The mineral is characterized by its monoclinic crystal system and often occurs as small, euhedral to subhedral crystals. Its color can range from yellow to brown, orange, or reddish-brown, depending on the presence of iron impurities. Clinohumite has a vitreous luster and a Mohs hardness of around 6. It is relatively dense, with a specific gravity of approximately 3.1 to 3.2.

Clinohumite was first discovered in 1876 in crystals from the Vesuvius volcano, Italy, and was named by G. G. Romanov in honor of Karl Friedrich Christian von Hünefeld, who in 1824 analyzed the mineral formerly called "humite." Subsequent studies revealed that what was previously thought to be a single mineral, humite, was actually a group of related minerals, with clinohumite being one of them. Its rarity and specific geological formation conditions make it of interest to mineralogists and collectors.