Muséum national d'histoire naturelle

GENERAL DESCRIPTION

Clinohumite is a mineral species that belongs to the humite group, a series of hydrated magnesium, iron, calcium, manganese and/or zinc silicates. It is found in contact metamorphism zones, in marbles and skarns. Some others are known in hydrothermal rocks.

Clinohumite is mainly found under grains within more or less compact aggregates, forming also prismatic crystals. Large and well-developed crystals are highly prized by collectors.

Its crystals are transparent to translucent. Their colour range from yellow to brown-reddish. They can be confused with hessonite (a variety of grossular garnet) because of their similarities in colour. In contrast, clinohumite shows a yellow to colourless pleochroism and can fluoresce in yellow-orange when illuminated by UV radiation (short waves).

Gem-quality samples have been discovered in the 1980’s, in the Pamir Mountains of Tajikistan. They are orange to brown-orange. Dark-reddish brown samples were recently found in the Taymyr area in Siberia. Mount Bischoff in Tasmania (Australia), the Vesuvio volcano in Italy or the Jacupiranga mine near Sao Paulo (Brazil) produced remarkable, although non gemmy crystals.

In France, clinohumite was found in Arignac (Ariège) and in the Costabonne mines (Pyrénées-Orientales).

The type-mineral is located in our Muséum National d'Histoire Naturelle in Paris (samples 106.395 et 106.556 from the Des Cloizeaux collection). It was found at the Monte Somma crater of the Vesuvio (Naples area in Italy). The mineral species was first described par Alfred des Cloiseaux in 1876.

Did you know? Clinohumite is, with chondrodite ((Mg,Fe)5(F,OH)2(SiO4)2), the two species of the humite series of minerals to be cut as a gem.

Clinohumite

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main description

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Mineralogy