Clinohumite is a mineral found as small grains in the marbles of contact metamorphic environments. It has been cut as a brilliant yellow-orange gemstone and is sought after by collectors because of its rarity. The intensity and the beauty of the orange color are important and inclusions are common and accepted. It was first discovered in the metamorphosed limestone blocks that were ejected by the volcano Mt. Vesuvius, near Napoli, in Italy.
Clinohumite is a fluorescent mineral and will glow a tan to yellow-orange color when subjected to shortwave UV light. It is similar in fluorescent color to the bright humite material found at Franklin, New Jersey. Humite is a related species to clinohumite as might be expected by their names. Clinohumite is named in allusion to its monoclinic symmetry as opposed to humite's orthorhombic symmetry. Clinohumite's structure is often intergrown with humite's structure in the same crystal
Clinohumite, like humite, is a member of the Humite Group of minerals. Class: Silicates , Subclass: Nesosilicates Group: Humite. Members of the humite group are noted for having a mixture of silicate and oxide layers in their structures. The silicate layers have the same structure as olivine and the oxide layers have the same structure as brucite. Clinohumite has four stacked olivine layers that alternate between the brucite layers. Associated Minerals include humite, talc, geikielite, lazurite, dolomite and calcite.
Crystal Habits include small prismatic or rounded crystals. Lamellar twinning is common. The luster is vitreous to resinous and the streak is white. Cleavage is poor and in one direction,- basal. Crystals are transparent to translucent and the fracture is brittle to conchoidal producing small conchoidal fragments.